Can't get highlight to work when mousing over object..

I have a grid of objects instantiated through a grid-making script. The script is attached to an empty gameobject in the scene.

Attached to each grid object (which appear as clones for some reason) is a script called "Highlight" which I'm trying to get to highlight each grid object green as I mouse over them. All that happens is the objects turn pink when instantiated and that's all. When I hover over them nothing happens either. I can assign the correct material to "normalColor" in the inspector which gets rid of the pink, but how do I get it to do this automatically? And how do I get my highlight working? Thanks! Total noob here.

 using UnityEngine;
 using System.Collections;
 
 public class Highlight : MonoBehaviour {
 
     public Renderer rend;
     public Material normalColor;
     public Color highlightColor;
 
     void Start () {
         rend = this.GetComponent<Renderer>();
         rend.material = normalColor;
     }
     
     void Update () {
         Ray ray = Camera.main.ScreenPointToRay (Input.mousePosition);
         RaycastHit hitInfo;
         if (Physics.Raycast (ray, out hitInfo, Mathf.Infinity)) {
             rend.material.color = highlightColor;
             Debug.Log ("moused over object");
         }
         else {
             rend.material = normalColor;
         }
     }
     
 //    void OnMouseOver () {
 //        //        Debug.Log (gameObject.name + " OnMouseOver");
 //        Debug.Log ("moused over object");
 //        rend.material.color = highlightColor;
 //    }
 //    
 //    void OnMouseExit () {
 //        //        Debug.Log (gameObject.name + " OnMouseOver");
 //        
 //        rend.material.color = normalColor;
 //    }
 
 }

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