diff --git a/src/ECS/Archetype/Archetype.cs b/src/ECS/Archetype/Archetype.cs
index 612493e2..543eb1e9 100644
--- a/src/ECS/Archetype/Archetype.cs
+++ b/src/ECS/Archetype/Archetype.cs
@@ -308,12 +308,12 @@ internal static void MoveLastComponentsTo(Archetype arch, int newIndex, bool upd
     }
     
     /// <remarks>Must be used only on case all <see cref="ComponentTypes"/> are <see cref="ComponentType.IsBlittable"/></remarks>
-    internal static void CopyComponents(Archetype arch, CopyContext context)
+    internal static void CloneComponents(Archetype arch, CopyContext context)
     {
         var sourceIndex = context.source.compIndex;
         var targetIndex = context.target.compIndex;
         foreach (var sourceHeap in arch.structHeaps) {
-            sourceHeap.CopyComponent(sourceIndex, targetIndex, context);
+            sourceHeap.CloneComponent(sourceIndex, targetIndex, context);
         }
     }
     
diff --git a/src/ECS/Archetype/StructHeap.cs b/src/ECS/Archetype/StructHeap.cs
index c48bc680..ac32db36 100644
--- a/src/ECS/Archetype/StructHeap.cs
+++ b/src/ECS/Archetype/StructHeap.cs
@@ -36,7 +36,7 @@ internal abstract class StructHeap : IComponentStash
     internal  abstract  void        ResizeComponents        (int capacity, int count);
     internal  abstract  void        MoveComponent           (int from, int to);
     internal  abstract  void        CopyComponentTo         (int sourcePos, StructHeap target, int targetPos);
-    internal  abstract  void        CopyComponent           (int sourcePos, int targetPos, in CopyContext context);
+    internal  abstract  void        CloneComponent           (int sourcePos, int targetPos, in CopyContext context);
     internal  abstract  void        SetComponentDefault     (int compIndex);
     internal  abstract  void        SetComponentsDefault    (int compIndexStart, int count);
     internal  abstract  object      GetComponentDebug       (int compIndex);
diff --git a/src/ECS/Archetype/StructHeap.generic.cs b/src/ECS/Archetype/StructHeap.generic.cs
index f2badfa9..33c8c4fc 100644
--- a/src/ECS/Archetype/StructHeap.generic.cs
+++ b/src/ECS/Archetype/StructHeap.generic.cs
@@ -78,14 +78,21 @@ internal override void CopyComponentTo(int sourcePos, StructHeap target, int tar
     /// <see cref="ComponentType"/>'s.<br/>
     /// If not <see cref="ComponentType.IsBlittable"/> serialization must be used.
     /// </remarks>
-    internal override void CopyComponent(int sourcePos, int targetPos, in CopyContext context)
+    internal override void CloneComponent(int sourcePos, int targetPos, in CopyContext context)
     {
         var copyValue = CopyValueUtils<T>.CopyValue;
+        ref var source = ref components[sourcePos];
+        ref var target = ref components[targetPos];
         if (copyValue == null) {
-            components[targetPos] = components[sourcePos];
+            target = source;
+        } else {
+            copyValue(source, ref target, context);
+        }
+        if (!StructInfo<T>.HasIndex) {
             return;
         }
-        copyValue(components[sourcePos], ref components[targetPos], context);
+        var targetEntity = context.target;
+        StoreIndex.AddIndex(targetEntity.store, targetEntity.Id, source);
     }
     
     internal  override  void SetComponentDefault (int compIndex) {
diff --git a/src/ECS/Entity/Store/Entities.cs b/src/ECS/Entity/Store/Entities.cs
index eebe6b6a..b187b0d9 100644
--- a/src/ECS/Entity/Store/Entities.cs
+++ b/src/ECS/Entity/Store/Entities.cs
@@ -92,13 +92,12 @@ public Entity CloneEntity(Entity entity)
         var clone       = new Entity(this, id, revision);
         
         // var isBlittable = IsBlittable(entity);
-
-        // todo optimize - serialize / deserialize only non blittable components and scripts
         // if (true) {
+        
         var scriptTypeByType    = Static.EntitySchema.ScriptTypeByType;
         // CopyComponents() must be used only in case all component types are blittable
         var context = new CopyContext(entity, clone);
-        Archetype.CopyComponents(archetype, context);
+        Archetype.CloneComponents(archetype, context);
         if (clone.HasComponent<TreeNode>()) {
             clone.GetComponent<TreeNode>() = default;   // clear child ids. See child entities note in remarks.
         }
@@ -109,7 +108,8 @@ public Entity CloneEntity(Entity entity)
             scriptClone.entity  = clone;
             extension.AddScript(clone, scriptClone, scriptType);
         }
-        /* } else {
+        /* keep old implementation using JSON serialization for reference
+        } else {
             // --- serialize entity
             var converter       = EntityConverter.Default;
             converter.EntityToDataEntity(entity, dataBuffer, false);
diff --git a/src/Tests/ECS/Entity/Test_Entity.cs b/src/Tests/ECS/Entity/Test_Entity.cs
index 8a933bbb..0808d4fd 100644
--- a/src/Tests/ECS/Entity/Test_Entity.cs
+++ b/src/Tests/ECS/Entity/Test_Entity.cs
@@ -4,6 +4,7 @@
 using System.Linq;
 using Friflo.Engine.ECS;
 using NUnit.Framework;
+using Tests.ECS.Index;
 using Tests.Utils;
 using static NUnit.Framework.Assert;
 
@@ -204,7 +205,7 @@ public static void Assert_TryGetEntityById()
     }
      
     [Test]
-    public static void Test_EntityStore_CloneEntity()
+    public static void Test_EntityStore_CloneEntity_1()
     {
         var store       = new EntityStore(PidType.RandomPids);
         var entity      = store.CreateEntity();
@@ -237,7 +238,7 @@ public static void Test_EntityStore_CloneEntity()
     }
     
     [Test]
-    public static void Test_EntityStore_CopyTo()
+    public static void Test_EntityStore_CloneEntity_2()
     {
         var store       = new EntityStore();
         var entity1      = store.CreateEntity();
@@ -250,6 +251,25 @@ public static void Test_EntityStore_CopyTo()
         AreNotSame(list1, list2);
     }
     
+    [Test]
+    public static void Test_EntityStore_CloneEntity_IndexedComponent()
+    {
+        var store   = new EntityStore();
+        var index   = store.ComponentIndex<IndexedInt,int>();
+        var entity = store.CreateEntity(1);
+        
+        entity.AddComponent(new IndexedInt { value = 42 });
+        var entities = index[42];
+        AreEqual(1,         entities.Count);
+        AreEqual("{ 1 }",   entities.Debug());
+        
+        var clone = store.CloneEntity(entity);
+        AreEqual(42, clone.GetComponent<IndexedInt>().value);
+        entities = index[42];
+        AreEqual(2,         entities.Count);
+        AreEqual("{ 1, 2 }",entities.Debug());
+    }
+    
     [Test]
     public static void Test_EntityStore_CloneEntity_component_exception()
     {