Cerith snails don't look like the pictures?

[CjAmaryllis]

I have 5 Cerith snails and a GSP in quarantine. I assume there's some hitchhiking algae there, and I spotted a vermetid snail on one. A few feather dusters or hydroids (can't tell) as well. But their shell structure looks completely different than all the pictures. Looks like build up of something! They all look like this.
Thanks!

 

[exnisstech]

Interesting. I can't help with an ID but a can tell you that looks nothing like the cerith snails I have.

 

[CjAmaryllis]

Interesting. I can't help with an ID but a can tell you that looks nothing like the cerith snails I have.

Yes! Nor any of the Google images of them show this

 

[Brit’s Fish]

I have gotten large Ceriths with very irregular looking shells like this before. Where did you get them from?
Reef Cleaners sells some called sticky Ceriths and their shells are pretty knobby and covered in coralline.
https://www.reefcleaners.org/aquarium-store/tank-cleaners/stocky-cerith-detail