please help to id this snail

[weileong]

Found this snail in my sump algae compartment.

Body is very white so I've to underexpose the algae so as not to saturate the body color in the photo.

I actually got a big shocked seeing white stuffs there for a moment tot my algae turn white liao.

Posted the same photo in my tank setup but thought post here more pple might see it.

Are they harmful? Hopefully not else I sure have problems picking them out.

Can see two babies sticking on it's body too, yee....

[weileong]

another one.

Got another few more I can see and I am sure got many more hiding under the algae!

Pray hard not harmful! Just eat algae will do then I don't need to trim the algae already.

[weileong]

searching high and low for info but cannot find.

Closest I can get is this

http://www.seaslugforum.net/volvayak.htm

[KingFish]

Its some kind of Caulerpa snails for sure, typically coming in with the Fern Caulerpa like the ones in the pictures.

They have very brittle, even soft shells.

No harm really except when disturbed or dying will release some chalky substance. No side effects on the corals and tank inhabitants noted.