Changing Object

Hello, what im trying to do is change one object into another. for example how would i code for the DemoGameTile to turn into a Demon. Thanks in advance

using Instantiate : Unity - Scripting API: Object.Instantiate

and Destroy : Unity - Scripting API: Object.Destroy

using UnityEngine;
using System.Collections;

public class MonsterTrigger : MonoBehaviour {
	
	public Transform demon;
	public Transform goblin;
	public Transform ogre;
	
	private Transform clone;

	
	void Start () {
	
	}
	
	void Update () {
	
	}
	
	void OnTriggerEnter(Collider other)
	{
		Vector3 clonePosition = new Vector3( 0.6096257f, 0.002073564f, -1.967801f );
		
	    switch( Random.Range(0, 4) )
	    {
	       case 0 :
	            clone = Instantiate( demon, clonePosition, Quaternion.identity) as Transform;
	       break;
	
	       case 1 :
	            clone = Instantiate( goblin, clonePosition, Quaternion.identity) as Transform;
	       break;
	
	       case 2 :
	            clone = Instantiate( goblin, clonePosition, Quaternion.identity) as Transform;
	       break;
	
	       case 3 :
	            clone = Instantiate( ogre, clonePosition, Quaternion.identity) as Transform;
	       break;
	    }
	
	    Destroy( gameObject );
	}
	
}