Can we anyhow store a prefab in a list when we collide into the instance of that prefab casted as gameObject?

@kushalagrawal890, Check out PrefabUtility.GetPrefabParent -- look at the documentation on this - it is supposed to return exactly what you want...

[Edit & correction]

This is an editor only function. There is no way to programmatically determine what prefab an object instance was Instantiated from. This does work in an Editor script, but not at runtime.

You can, at the time you create the instance store a reference to the prefab in a script on the object. (probably the simplest method to track and object and it's prefab.)

So, create a script on your instanced object with a public GameObject myPrefab field.

Then at the time you Instantiate the prefab:

       // assume you have a prefab reference in a public field thusly:
       public GameObject prefabObject;
       // then assume you have a script "ObjectScript.cs" as a 
       //component on the prefab that contains this:<br><br>
       public GameObject prefabObject;
       // then where you instantiate the object
       GameObject gO = (GameObject) Instantiate( prefabObject );
       ObjectScript oS = gO.GetComponent<ObjectScript>();
       // now store a reference to the prefab on the newly
       //instantiated gameObject:
       oS.prefabObject = prefabObject;

There are definitely other ways to do it. For example, if you want to store prefabs in a list, and in a corresponding list the gameObject instances, and associate the two list by their indices, for one.