I considered slime mold but it's wrong texture. Probably one of the cooler things to find at leastHuh, I would not have guessed freshwater sponge. Of course, I had no idea that might be a possibility.
As for the crabby cichlids, nobody like change, especially territorial fish.
Freshwater Sponges — In Defense of Plants
www.indefenseofplants.com
Freshwater Sponges (U.S. National Park Service)
Mysterious creatures often mistaken for algae, freshwater sponges are sensitive organisms that only grow in healthy streams.
www.nps.gov