What is this?

[bandos507]

Hi!

This thing moves around all my tank constantly.. On the walls and rocks. Any ideas what it is?

 

[Lionfish Lair]

That's a fleshy limpet.

 

[NanaReefer]

I knew she'd know [emoji38]

 

[bandos507]

Are they harmful??

 

[NanaReefer]

Mostly algae grazers, that includes coralline. Few survive long term in aquariums.