how to make a match 3 game where 3 objects of the same kind are touching, can be clicked and destroyed.

using UnityEngine;
using System.Collections;

public class DestroyBlock : MonoBehaviour {
    
    public GameObject destroyableBlock;
    public GameObject destroyableBlock2;
    public GameObject destroyableBlock3;
    
    public void OnMouseDown()
    {
        if(destroyableBlock == null || destroyableBlock2 == null || destroyableBlock3 == null)
        {
            return;
        }
        else
        {
            Destroy(destroyableBlock);
            Destroy(destroyableBlock2);
            Destroy(destroyableBlock3);
        }
    }
}