Maybe flatworm??? All over rocks - please help!!!

[jaihutcherson]

Hey all,

The pictures describe much better than I can. They look like some sort of flat worm that have attached to all my rocks in less than 3 days. There are well over 50 at this point, still growing and still multiplying. Please advise as to what they are and what, if anything, I need to do to get rid of them. Thanks for all the help.
Jai

 

[sunken3]

looks like an algae growth, Are you sure it's a critter?

 

[jaihutcherson]

After posting found some info others had posted with some of the heavy hitters chiming in. Looks like a black sponge will be the answer. From what I’ve read not harmful as other sponges can be. Suggested to remove rock and scrub or inject vinegar to kill. Thanks to those before me that got or gave the answers.

 

[sunken3]

that doesn't look like black sponge. I have had black sponge in my aquarium. that looks more like a calcifying algae. but the color is hard to tell. As long as your happy with your answer. good luck!