This thing is about an inch tall and hard, if i remember correctly it came off some rock witch the guy at the store said was Florida rock. It has grown about a cm or two in the last month, it has wedged itself in this rock where i have it now. I wonder if i should have stronger flow in it? I think it eats phytoplankton or the micro-vert witch I already use in the tank.. Because like i said ive had it for atleast a year.