Are these vermatid snails?

[Joe31415]

Whatever they are I just noticed them today. I didn't think they were anything alive, but I was still curious where they came from.

Just now, when I was taking this picture, I noticed something sticking out of one of them. My initial thought was that a (large) pod or a bristleworm got into one, but I don't think that's the case.
The thing waving around appears to be doing so under it's own power, not because water is moving past it.

I don't think they're actually vermatids, but it might answer my question as to why I lost all the polyps on part of the coral just above it (though I'm fairly sure it was just the urchin going over the top of it one day). But maybe why two of four heads on one random euphyllia decided to bailout even though everything else in the tank is fine?

EDIT: that second picture is a video. You might have to click on it to get it started.

 

[Sshannon]

The one higher on the rock looks like a vermetid to me

 

[ISpeakForTheSeas]

I think those are spionid (taxonomic family Spionidae) worms - the two tentacles you see poking out and moving around in the second video are the palps (feeding tentacles) of the worm. They’re generally harmless, but can be ugly in large numbers and - in some cases - they bore through corals (typically SPS, but occasionally LPS). These don’t seem to kill coral typically, but they likely would irritate them, and I’d imagine if you got a sensitive or unhealthy one they potentially could kill it:

Coral Boring Spionid Worms -- an ugly bane to SPS

This is not something I've ever seen before. They are extremely ugly. Mar the appearance of SPS. This is on a "Beach Bum" encrusting montipora. I would take aphasia or even montipora eating nudibranchs over this crap. I've beat those with hard work. Not sure how to eliminate these without...

www.reef2reef.com

 

[Joe31415]

Could be. Last night I happened to notice that even though it looks like a little pimple, it's actually a very tiny spiral shell(?). In any case, the next time I'm in the tank, I'll see if I can snap it off or crush it (and hopefully not end up with 20 more).