white snail id

These snails are everywhere in my tank in all kinds of sizes and appear to only be active at night. Are they coral pests or beneficial hitch hikers?

Hi - thanks in advance for the help! Snail- it’s very small- notice the sand size Is this next one the common starfish we always see? It just looks different than the white ones I’ve had. Ignore the superglued vermetid snail in the picture.