Looking for an ID on these 2 inverts

[Hunna]

The little snail on my sand conch’s shell

And whatever this thing is on my frag rack

 

[chaples55]

Collonista snail and some kind of limpet. I have both and both are good guys.

 

[SaltedCarmel]

Collonista snail and some kind of limpet. I have both and both are good guys.

+1 to this. Have heard some say collonista snails can become a pest if they breed too much, but in my experience they’re good guys. Limpets are awesome!