Possible coral eaters?

[Playdope]

Are these a potential threat to corals? I am trying to find anything I can that may be eating the zoanthids. I notice at lights out that a bunch of these really tiny snails come out. They're like the size of an eraser tip.

Also, to me, anything in the tank that looks like a transparent bug and moves relatively quick is a "pod". Can someone tell me if the one pictured below is a coral eater, or if any are?

I am terrible at picturing things up close.. and i dont have manual focus, so I'll just post a bunch, and maybe one of the pictures will allow you to ID what I've got here... thanks

 

[Playdope]

Here are some more pics of a bunch of the snails:

What type of snail is this? Is it possible they could be eating my zoanthids?

It seems there are a ton of them... is the only way to get them to suck them up one by one with a baster?

Thanks

 

[dubbin1]

I also have tons of these little snails and they are harmless. I asked what they were at one time but I forgot the answer. All I remember is that I was told they are harmless and many people have them.

 

[Mihai]

Yup, I have tons, great herbivores!
M.

 

[Playdope]

Are they collinista?

 

[Mihai]

Are they collinista?

Yup, not sure on the spellng, but it's the correct species.
M.

 

[Sugar Magnolia]

Looks like collinistas to me too.

Heliacus snails tend to have a dark brown/black color to the mottled areas. The collonista's tend to be tan to med brown and stay tiny. 3/8" or so when fully grown. They also breed like crazy. 8) Mine are referred to as the night shift. Hundreds of them come out after lights out to graze.

 

[Ninong]

Those appear to be Collonista sp. trochids. I have hundreds of them in my 120-gal reef aquarium. They are very tiny (3-6mm) and rather attractive under a magnifying glass but they are a nuisance as far as I am concerned.

They are strictly nocturnal, coming out onto all exposed surfaces in the aquarium (rock, glass, etc.) around dusk and retiring to their hiding places well before dawn. They appear to be herbivores grazing on algal films. Unfortunately, there are so many of them (several hundred) that they deny needed nutrition to other more desirable trochids in my tank. Their numbers seem to fluctuate between about 800 at the high end and 300 at the low end. They are impossible to completely remove because they are so small and because they are in every nook and cranny in the tank.

Dr. Ron Shimek discusses them in this article: http://reefkeeping.com/issues/2004-05/rs/index.htm

 

[Anonymous]

I have about a thousand of them. They really come out at night. They do not harm corals. Had them for years without problems.