i think your right. i looked at some pics on planet inverts and im prettu sure thats what these are.
i go in and out of bad snail problems, but i never over feed, i swear. i feed MAYBE every other day and when i do feed its minimal. i sprinkle a tiny bit of crushed flakes, wait till they are all eaten, then do it again. when some wasted food floats to the bottom i feed a tiny bit more (i know the shrimps will clean up the wasted food) and then thats it.