Snail ID please

[jinenon]

These guys are taking over my glass and im getting worried. They resemble the sundials that i know are zoo eaters but their shells are just a little different. But, they are still real small. I have noticed that the tentacles on my zoos, lately, look like the tentacles are falling off or just plain disappearing. It doesnt kill the zoo but they just dont look as healthy as they use to. You can actually see the rim of the zoo rather than the tentacles attached to the rim. I havent lost any zoos yet but they dont seem to be multiplying as fast as they use to. Any help on the ID of these snails and what might be happening to my zoos would be great. Also, what do the sundials eat first? The stalks or the tentacles? Thanks!!

Jesse

PS-I know the pics arent great but its all i got....sorry