Just showed up couple days ago. Haven't put anything new in for a bit. Not sure what it is. It's "head" is kinda like a flower. Just flows. It's connected to a tube like body that is striped.
Looks like a qtip sponge (they are sponges right?) but its really blurry to be definite, thats my guess though. Also, if thats what they are, they are harmless filter feeders/