Exploding a Mesh into a bunch of triangles with Rigidbodies. (from http://answers.unity3d.com/questions/1006318/script-to-break-mesh-into-smaller-pieces.html)

TriangleExplosion

using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 
 public class TriangleExplosion : MonoBehaviour {
 
     public IEnumerator SplitMesh (bool destroy)    {
 
         if(GetComponent<MeshFilter>() == null || GetComponent<SkinnedMeshRenderer>() == null) {
             yield return null;
         }
 
         if(GetComponent<Collider>()) {
             GetComponent<Collider>().enabled = false;
         }
 
         Mesh M = new Mesh();
         if(GetComponent<MeshFilter>()) {
             M = GetComponent<MeshFilter>().mesh;
         }
         else if(GetComponent<SkinnedMeshRenderer>()) {
             M = GetComponent<SkinnedMeshRenderer>().sharedMesh;
         }
 
         Material[] materials = new Material[0];
         if(GetComponent<MeshRenderer>()) {
             materials = GetComponent<MeshRenderer>().materials;
         }
         else if(GetComponent<SkinnedMeshRenderer>()) {
             materials = GetComponent<SkinnedMeshRenderer>().materials;
         }
 
         Vector3[] verts = M.vertices;
         Vector3[] normals = M.normals;
         Vector2[] uvs = M.uv;
         for (int submesh = 0; submesh < M.subMeshCount; submesh++) {
 
             int[] indices = M.GetTriangles(submesh);
 
             for (int i = 0; i < indices.Length; i += 3)    {
                 Vector3[] newVerts = new Vector3[3];
                 Vector3[] newNormals = new Vector3[3];
                 Vector2[] newUvs = new Vector2[3];
                 for (int n = 0; n < 3; n++)    {
                     int index = indices[i + n];
                     newVerts[n] = verts[index];
                     newUvs[n] = uvs[index];
                     newNormals[n] = normals[index];
                 }
 
                 Mesh mesh = new Mesh();
                 mesh.vertices = newVerts;
                 mesh.normals = newNormals;
                 mesh.uv = newUvs;
                 
                 mesh.triangles = new int[] { 0, 1, 2, 2, 1, 0 };
 
                 GameObject GO = new GameObject("Triangle " + (i / 3));
                 GO.layer = LayerMask.NameToLayer("Particle");
                 GO.transform.position = transform.position;
                 GO.transform.rotation = transform.rotation;
                 GO.AddComponent<MeshRenderer>().material = materials[submesh];
                 GO.AddComponent<MeshFilter>().mesh = mesh;
                 GO.AddComponent<BoxCollider>();
                 Vector3 explosionPos = new Vector3(transform.position.x + Random.Range(-0.5f, 0.5f), transform.position.y + Random.Range(0f, 0.5f), transform.position.z + Random.Range(-0.5f, 0.5f));
                 GO.AddComponent<Rigidbody>().AddExplosionForce(Random.Range(300,500), explosionPos, 5);
                 Destroy(GO, 5 + Random.Range(0.0f, 5.0f));
             }
         }
 
         GetComponent<Renderer>().enabled = false;
         
         yield return new WaitForSeconds(1.0f);
         if(destroy == true) {
             Destroy(gameObject);
         }
 
     }
 
 
 }