These snails started coming out at night.

[Oldsalt]

Hello folks

These snails have exploded in population of late and only come out at night. Are these sundial snails? They're everywhere!
If so, are they bad news? If they are bad, how do I control their population? Obviously I don't want to harm the urchin.
The 2nd photo is the same rock during the day.

TIA
Bill

 

[WVNed]

Do they look like these.

I have millions of them that come out at night of different sizes but they never get larger than about 1/4 on an inch. They have never bothered anything, but they are tough on my pumps.

During the day they pile up in places

I think these are collonista snails.