strange bug on live rock

so i just noticed a weird little "bug" living under some zoa's on my live rock.
i didn't get all that good of look at it but it was fairly small, maybe about the size of a pencil eraser, it had two antenna and when it was aggravated it sprayed out a cloudy smoke looking substance...it did that multiple times.

any idea of what it might be? i couldn't get a pic because it retreated back under the zoa.

 

From what I found online, it may be a snail's mating ritual, and the white smoke was probably sperm. Not an expert, but that's just what I found searching for this online.

Can anyone confirm this?

 

Sounds like a stomatella snail. If had a half shell that could be the ID.

 

that may be it, sadly i didn't get a look at the whole thing, just its face. but the stomatella snails i looked up have been a yellowish color, this guy was more grey and black with real thin antenna. i am guessing it isn't a problem, he must have been in there for quite some time now. it just kinda freaked me out when it shot out a bunch of "smoke" when i was cleaning off the rock near it.

 

My stomatella's are more greyish in color,if thats what yours are,they're good to have.I have also seen them blow sperm clouds into the water.I call them snails on the half shell.

 

could be a few differant things in Your tank... here a place i go to

Link: Indo Pacific Snails

Best of luck...

 

its a stomatella. they range from literally looking EXACTLY like rock to a bright yellow with silvery shell. either way, they are IMO the best cleaners in the tank. The white stuff was a release of gametes which will eventually find their way into your rock and slowly grow into more stomatella. In about 2-3 months you will have many more popping up

 

Well that blew my research out of the water!!! (no pun intended)

 

Stomatella snails (stomatella is a genus) have the species name "varia" because of the multitude of colors they can be.