Any idea what this snail is

[LxHowler]

I've been sent a photo by a friend asking what sort of snail these are, he said he's been having some issues with hair algae recently and as it's dying back he's started to see these.
Said the only snails in the tank are trochus and nasarius snails but these don't look like either of these so I thought I ask on here because I'm not sure.
He also said they only seem to be eating algae none near the corals so hopefully they are a good thing.
Anyone have any ideas. Thanks

 

[brmreefer]

Collonista Snail maybe?

 

[LxHowler]

Collonista Snail maybe?

Just googled them. Looks like it could be them. Are they anything to worry about?

 

[Isopod80]

+1 Collonista, very common. Harmless algae eaters.

 

[minus9]

Collonista indeed. Their population comes and goes, also are mostly nocturnal. Enjoy the micro CUC!