HELP! What is...

[molodets]

Look what I found. Its a small Snail (photo is bad) the shell has black and white colors.
is it good, BAD?

and found another NudiBranch, its huge...
I took it out.
Any more advice?

 

[Bryceandmandy]

The snail is too small and blurry to see, google sundial snails. If it looks like that get rid of it, they irritate zoas pretty badly. My buddy had some that used to cover them with eggs. Id removed the nudibranchs and look arpund for little white gel spirals around the tank. Tgose are the eggs. Nudis can be destructive. There are a few good threads on here that offer more info. Zoaid.com has an okay list of some common coral irritating pests.