sundial

What type of snail is this? I’m thinking sundial.

Hello there! So not going to lie here I'm a little concerned about my father's reef tank. He started a tank last year in December, and after I considered it fish friendly. He went out and got a couple fish and a couple corals, threw them in the tank and called it good. I visit when I can but he...

I found a couple tiny snails on some live rock. At first I thought they were sundial... but im thinking collonista now. Second opinion please.

Hey all, wanted to confirm that this was a collonista snail and not a sundial. Thanks for your input. Hope the image is okay.