Got some bad news for you.... its an albino strain of black/brown beard algea.... So you know what that means... TANK DISTRUCTINON AHAHAHAHAHHHHHHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!1111 No like srsly, this stuff is slow to grow, but it does NOT DIE. the white strain of this algea prefers places where water movement is miniamal. that is why its building up on the inside of the cave. But sure enough, it WILL SPREAD like a alien infestation... AND NOTHING will stop it. Im srs. this stuff is so resiliant its not even funny... It can even live in water with algeacide in it for a while. Take that pot out and bleach the **** out of it before its too late.