What is this?

[Danny N]

This "hairy, prickly" creature showed up recently. I haven't added anything in a few months. Could it possibly be a snail that has crawled out of its shell?

 

[bklynreef123]

hard to tell from the pic but with the pic and your description maybe its a Nudi?

 

[Lionfish Lair]

How does it move? That looks suspiciously like two eyes, there on the left.

 

[Danny N]

It moves just like a snail. I've seen it climbing my glass walls as well.

 

[Danny N]

Here is a picture of it climbing the wall

 

[BluewaterLa]

Cerith snail with some type of growth on its shell.

 

[jetmaker]

Looks like a sea hare

 

[Lionfish Lair]

It's hydroids on a snail.