These little idiots are really fun to watch while they try to balance sand or rocks on their heads. They've mowed down any hair algae I can see (can't comment on bubble since I don't have any). They bury into the sand, under mushroom rocks, climb up onto the bigger rocks slowly, and are very active, albeit slow.
Haven't had any issues so far with predation on anything
Haven't had any issues so far with predation on anything