code: function () {
      var defaultMaterial = new THREE.MeshBasicMaterial();
      var material = this.material;
      var object3D = this.el.getObject3D('mesh');
      if (object3D) { object3D.material = defaultMaterial; }
      disposeMaterial(material, this.system);
    }
docs: Remove material on remove (callback).
  Dispose of it from memory and unsubscribe from scene updates.