If you can use a blender you want to, but you dont make a soup out of them , just enough to cut them into small pieces, not a very good option.
another option is cut them in four and use a coarse veil or a net and tide them loosely w a rubber band, they should attach to the rock in a week or two. give them a lot of flow or they will catch a fungus.
here is a good info:
http://www.garf.org/ricord/ricord.html