Collonista or Sundial Snails?

[wlmalek]

Just passed by the tank with flashlight and found these snails. Are they Collonista or Sundial?
I had a event months ago where I lost a whole zoa rock in matter of days.
something telling me they did it.but, I maybe wrong.

 

[blaxsun]

Collonista supposedly only grow to about 1/4" and wouldn't go after the zoas (they just get in all the equipment). Sundial snails would go after the zoas (and other corals), so since you lost some corals I'm leaning towards those.

 

[kjkszpj9]

If the snail moves with its shell upright its a sundial if it just lays flat when it moves its most likely a collonista snail.