Some sort of barnacle?

[John Mills]

This was not on this hammer coral when we bought it. It was dipped before adding it to the tank, we were looking down from the top of the aquarium when we noticed this on the back side. I turned it around for a better picture.

 

[EriksOasis]

Looks like a tube worm. Harmless filter feeder. Uses calcium to form its tube.

 

[John Mills]

Thanks EricksOasis, I'll keep an eye on it.

 

[DSC reef]

That looks like a vermetid worm, that mucous can irritate the coral. I'd plug it up soon. Tube worms are harmless filter feeders but vermetid are not.

 

[Legal Reefer]

Hopefully someone with more experience with me will chime in to verify what it is, but I think it might be a vermetid snail. I just broke one off my hammer a couple days ago. My pic is hard to make out but I think it's the same. Looked like it was irritating my hammer. Kept seeing a hair like strand of mucus or something coming out of it going across the hammer. I removed the strand, but when I would check back there was another strand. It might just be foraging for detritus, but I didn't want to take any chances. If you look up vermetid snail there will probably be some pics that look like yours.

 

[Legal Reefer]

Oops..pic

 

[DSC reef]

The op's pic is a vermetid worm/snail.

 

[EriksOasis]

You’re right. How would you get rid of them?

 

[DSC reef]

If it's on the frag plug I'd put a generous amount of reef glue in the opening, that would be easiest.

 

[Shaddow_wolf169]

Glue it shut

 

[Legal Reefer]

I tried to scrape mine off but it was too hard. Ended up crushing the outside with needlenose pliers then scraping it off. I would suggest gluing the opening as the others suggested. The trunk of my hammer is very brittle and I ended up breaking off the portion with the snail on it. While it didn't hurt my hammer, I just got lucky.