What are these in my sump

[Yates273]

Was doing a water change and staring at my sump. I noticed these little white marks that I thought were chitons until I took a closer look. They are little white “worms” that were moving around on the walls. Are these ghost white worms. If not what are they and should I be concerned?

 

[Dread Pirate Dave]

Stometella snails or maybe limpetts.

 

[Yates273]

I thought maybe limpets but they don’t have a shell like the limpets.

 

[Yates273]

Stometella snails or maybe limpetts.

You know what upon closer review they look like they do have a small shell. Guess they are limpets. Thanks