Marc Weiss F.O.R.M. (Funky Old Reef Mud), 8.5 oz. Nature's source of trace elements and microbial stimulants - without chemicals. Safe and bioavailable! F.O.R.M. is the best natural source of those things that aquarists have been trying to put in their reef aquariums for years. F.O.R.M. supercharges microbial activity in all marine aquariums.