Anyone ever heard of of this? I just saw it at the Farm and Fleet and the ingredients really didn't tell me what the heck it was other than a little weird looking. I don't know if the Cherry Stone part was the brand name or the type of grit, in which case it is probably something made out of cherry pits... Just curious....Thanks in advance! Oh, can oyster shell be used as grit? or do I need a separate grit too?