Critter ID

[efroggies]

I was doing a water change tonight and found these critters that look like slugs, nudis, snails with out shells you know kinda generic. I pulled them out to get a good pic, the link is below. Does anyone know what they are and if they are harmful or helpful?

http://i5.photobucket.com/albums/y18...slugthings.jpg

[Psychojam]

I have the same kind of thing in my tank. I only see it at night. Curious to see what others say.

[cilyjr]

its a stomatella its harmless.

http://www.melevsreef.com/id/stomatella.html

[efroggies]

No I have seen those and have those. These have no shell whatsoever.

[bertoni]

I don't see any signs of a shell, either. My best guess would be a slug, not a nudibranch, with an unknown diet, but perhaps an algae-eater. I don't know enough about sea slug biology to say much.

[hybridgenius]

Its a nudibranch. It will just eat algae... I wouldnt worry too much.

[bertoni]

If it's a nudibranch, it won't eat algae. Nudibranchs are all predatory. I don't see any gill structure, so I am not convinced it's a nudibranch, but it might be.

[efroggies]

Yeah they dont seem to have gill structures of any kind. They only seem to have two antennae at the "head" end where the mouth is.

[greenbean36191]

They look like sacoglossans, but from the picture there's also a slight chance they could be arminid nudibranchs. The former would be good, the latter bad. A side view would help settle this. What were they on when you found them?