Anyone have any clue on this hitchhiker. he's been in my tanks for as long as I've had the live rock he' attached to. Hasn't bothered anything and has been about that size for at least five years.
Those pics look like they are really irritated by something in the system. When my acans act something like that its usually because they have been irritated by nearby zoas and are looking to attack or I've let my alkalinity slip between water changes. Sometimes knocking some salt creep back...
It looks angry like its trying to attack something nearby. My echinata does that sometimes when it senses the chalice thats growing about six inches above it. Alkalinity fluctuations can also make acans do that.
the latest picture by your pump is a stomatella, good guy keep it. The ones under what looks like a baggie in the picture look like colonista snails. Good grazers but can be prolific.