diff --git a/Engine.Core/Abstract/IBehaviourCollector.cs b/Engine.Core/Abstract/IBehaviourCollector.cs
index 9c2ecc9..fa016d4 100644
--- a/Engine.Core/Abstract/IBehaviourCollector.cs
+++ b/Engine.Core/Abstract/IBehaviourCollector.cs
@@ -1,5 +1,3 @@
-using System.Collections.Generic;
-
 namespace Syntriax.Engine.Core;
 
 /// <summary>
@@ -19,6 +17,16 @@ public interface IBehaviourCollector<T> : IHasUniverse where T : class
     /// </summary>
     event RemovedEventHandler? OnRemoved;
 
+    /// <summary>
+    /// Amount of <typeparamref name="T"/> collected.
+    /// </summary>
+    int Count { get; }
+
+    /// <summary>
+    /// Get a <typeparamref name="T"/> collected by it's index.
+    /// </summary>
+    T this[System.Index index] { get; }
+
     /// <summary>
     /// Delegate for handling the <see cref="OnCollected"/> event.
     /// </summary>
diff --git a/Engine.Core/ActiveBehaviourCollector.cs b/Engine.Core/ActiveBehaviourCollector.cs
index 3b16125..3ab81dd 100644
--- a/Engine.Core/ActiveBehaviourCollector.cs
+++ b/Engine.Core/ActiveBehaviourCollector.cs
@@ -1,4 +1,3 @@
-using System;
 using System.Collections;
 using System.Collections.Generic;
 
@@ -16,7 +15,6 @@ public class ActiveBehaviourCollector<T> : IBehaviourCollector<T> where T : clas
     protected readonly List<T> activeBehaviours = new(32);
     protected readonly Dictionary<IActive, T> monitoringActiveToBehaviour = new(32);
 
-    public IReadOnlyList<T> Behaviours => activeBehaviours;
     public IUniverse Universe { get; private set; } = null!;
 
     public ActiveBehaviourCollector() { }
@@ -117,4 +115,7 @@ public class ActiveBehaviourCollector<T> : IBehaviourCollector<T> where T : clas
         OnUnassigned?.Invoke(this);
         return true;
     }
+
+    public int Count => activeBehaviours.Count;
+    public T this[System.Index index] => activeBehaviours[index];
 }
diff --git a/Engine.Core/BehaviourCollector.cs b/Engine.Core/BehaviourCollector.cs
index 84da28a..6075ec5 100644
--- a/Engine.Core/BehaviourCollector.cs
+++ b/Engine.Core/BehaviourCollector.cs
@@ -1,4 +1,3 @@
-using System;
 using System.Collections;
 using System.Collections.Generic;
 
@@ -14,7 +13,6 @@ public class BehaviourCollector<T> : IBehaviourCollector<T> where T : class
 
     protected readonly List<T> behaviours = new(32);
 
-    public IReadOnlyList<T> Behaviours => behaviours;
     public IUniverse Universe { get; private set; } = null!;
 
     public BehaviourCollector() { }
@@ -96,4 +94,7 @@ public class BehaviourCollector<T> : IBehaviourCollector<T> where T : class
         OnUnassigned?.Invoke(this);
         return true;
     }
+
+    public int Count => behaviours.Count;
+    public T this[System.Index index] => behaviours[index];
 }
diff --git a/Engine.Core/Systems/DrawManager.cs b/Engine.Core/Systems/DrawManager.cs
index d924f37..2d05c91 100644
--- a/Engine.Core/Systems/DrawManager.cs
+++ b/Engine.Core/Systems/DrawManager.cs
@@ -11,20 +11,20 @@ public class DrawManager : UniverseObject
 
     private void OnPreDraw(IUniverse sender)
     {
-        for (int i = preDrawEntities.Behaviours.Count - 1; i >= 0; i--)
-            preDrawEntities.Behaviours[i].PreDraw();
+        for (int i = preDrawEntities.Count - 1; i >= 0; i--)
+            preDrawEntities[i].PreDraw();
     }
 
     private void OnDraw(IUniverse sender)
     {
-        for (int i = drawEntities.Behaviours.Count - 1; i >= 0; i--)
-            drawEntities.Behaviours[i].Draw();
+        for (int i = drawEntities.Count - 1; i >= 0; i--)
+            drawEntities[i].Draw();
     }
 
     private void OnPostDraw(IUniverse sender)
     {
-        for (int i = postDrawEntities.Behaviours.Count - 1; i >= 0; i--)
-            postDrawEntities.Behaviours[i].PostDraw();
+        for (int i = postDrawEntities.Count - 1; i >= 0; i--)
+            postDrawEntities[i].PostDraw();
     }
 
     protected override void OnEnteringUniverse(IUniverse universe)
diff --git a/Engine.Core/Systems/UpdateManager.cs b/Engine.Core/Systems/UpdateManager.cs
index 17bd49a..1380866 100644
--- a/Engine.Core/Systems/UpdateManager.cs
+++ b/Engine.Core/Systems/UpdateManager.cs
@@ -46,20 +46,20 @@ public class UpdateManager : UniverseObject
             toCallFirstFrameUpdates.RemoveAt(i);
         }
 
-        for (int i = preUpdateEntities.Behaviours.Count - 1; i >= 0; i--)
-            preUpdateEntities.Behaviours[i].PreUpdate();
+        for (int i = preUpdateEntities.Count - 1; i >= 0; i--)
+            preUpdateEntities[i].PreUpdate();
     }
 
     private void OnUpdate(IUniverse sender, UniverseTime engineTime)
     {
-        for (int i = updateEntities.Behaviours.Count - 1; i >= 0; i--)
-            updateEntities.Behaviours[i].Update();
+        for (int i = updateEntities.Count - 1; i >= 0; i--)
+            updateEntities[i].Update();
     }
 
     private void OnPostUpdate(IUniverse sender, UniverseTime engineTime)
     {
-        for (int i = postUpdateEntities.Behaviours.Count - 1; i >= 0; i--)
-            postUpdateEntities.Behaviours[i].PostUpdate();
+        for (int i = postUpdateEntities.Count - 1; i >= 0; i--)
+            postUpdateEntities[i].PostUpdate();
     }
 
     private void OnFirstFrameCollected(IBehaviourCollector<IFirstFrameUpdate> sender, IFirstFrameUpdate behaviourCollected)
diff --git a/Engine.Physics2D/PhysicsEngine2D.cs b/Engine.Physics2D/PhysicsEngine2D.cs
index 511ecd0..ae9a5e9 100644
--- a/Engine.Physics2D/PhysicsEngine2D.cs
+++ b/Engine.Physics2D/PhysicsEngine2D.cs
@@ -28,32 +28,32 @@ public class PhysicsEngine2D : UniverseObject, IPhysicsEngine2D
     {
         float intervalDeltaTime = deltaTime / IterationPerStep;
 
-        for (int i = physicsPreUpdateCollector.Behaviours.Count - 1; i >= 0; i--)
-            physicsPreUpdateCollector.Behaviours[i].PrePhysicsUpdate(deltaTime);
+        for (int i = physicsPreUpdateCollector.Count - 1; i >= 0; i--)
+            physicsPreUpdateCollector[i].PrePhysicsUpdate(deltaTime);
 
-        for (int i = physicsUpdateCollector.Behaviours.Count - 1; i >= 0; i--)
-            physicsUpdateCollector.Behaviours[i].PhysicsUpdate(deltaTime);
+        for (int i = physicsUpdateCollector.Count - 1; i >= 0; i--)
+            physicsUpdateCollector[i].PhysicsUpdate(deltaTime);
 
         for (int iterationIndex = 0; iterationIndex < IterationPerStep; iterationIndex++)
         {
             // Can Parallel
-            for (int i = rigidBodyCollector.Behaviours.Count - 1; i >= 0; i--)
-                StepRigidBody(rigidBodyCollector.Behaviours[i], intervalDeltaTime);
+            for (int i = rigidBodyCollector.Count - 1; i >= 0; i--)
+                StepRigidBody(rigidBodyCollector[i], intervalDeltaTime);
 
             // Can Parallel
-            for (int i = colliderCollector.Behaviours.Count - 1; i >= 0; i--)
-                colliderCollector.Behaviours[i].Recalculate();
+            for (int i = colliderCollector.Count - 1; i >= 0; i--)
+                colliderCollector[i].Recalculate();
 
             // Can Parallel
-            for (int x = 0; x < colliderCollector.Behaviours.Count; x++)
+            for (int x = 0; x < colliderCollector.Count; x++)
             {
-                ICollider2D? colliderX = colliderCollector.Behaviours[x];
+                ICollider2D? colliderX = colliderCollector[x];
                 if (!colliderX.IsActive)
                     continue;
 
-                for (int y = x + 1; y < colliderCollector.Behaviours.Count; y++)
+                for (int y = x + 1; y < colliderCollector.Count; y++)
                 {
-                    ICollider2D? colliderY = colliderCollector.Behaviours[y];
+                    ICollider2D? colliderY = colliderCollector[y];
 
                     if (!colliderY.IsActive)
                         continue;
@@ -65,8 +65,8 @@ public class PhysicsEngine2D : UniverseObject, IPhysicsEngine2D
             OnPhysicsIteration?.Invoke(this, intervalDeltaTime);
         }
 
-        for (int i = physicsPostUpdateCollector.Behaviours.Count - 1; i >= 0; i--)
-            physicsPostUpdateCollector.Behaviours[i].PostPhysicsUpdate(deltaTime);
+        for (int i = physicsPostUpdateCollector.Count - 1; i >= 0; i--)
+            physicsPostUpdateCollector[i].PostPhysicsUpdate(deltaTime);
 
         OnPhysicsStep?.Invoke(this, deltaTime);
     }
@@ -104,9 +104,9 @@ public class PhysicsEngine2D : UniverseObject, IPhysicsEngine2D
                 if (!colliderX.IsActive)
                     continue;
 
-                for (int y = 0; y < colliderCollector.Behaviours.Count; y++)
+                for (int y = 0; y < colliderCollector.Count; y++)
                 {
-                    ICollider2D? colliderY = colliderCollector.Behaviours[y];
+                    ICollider2D? colliderY = colliderCollector[y];
 
                     if (!colliderY.IsActive)
                         continue;