Barnacle?

[MegabiteOG]

Found this thing and seemed to be munching on an acro. I put it in a tray in the sump for now, but is it friend or foe? Looks like a barnacle.

 

[19Mateo83]

It’s a keyhole limpet. They are usually algae grazers and good part of the cleanup crew but there are a couple types that can eat polyps when algae runs low.

 

[rayadog]

^Agreed. A barnacle, sessile shouldn’t be a problem either. Just a filter feeder.

 

[tripdad]

Limpet

 

[MegabiteOG]

Thanks all for the responses. Limpet it is. I have very very little algae in the tank, so maybe that’s why it was on the acro.