The amount of little critters that crawl all of over the rock and glass. My bigger tank has been running for awhile with mature rock, I only recently added one fish, so the "buggies" have been reproducing to epic proportions. I need to figure out a lid situation before I add the wrasse and mandarin on my list. :::wink wink nod nod:::: Cant wait to watch them go to town and get big fat bellies.TANK TALK: What’s the coolest surprise you’ve discovered in or about your aquarium?