Killer snail? Please ID

[doboy]

This guy was a hitchiker on some green mushrooms. Is he a a good guy or a bad guy? His shell is sort of shaped like a barnacle -- with a pointed top.

 

[sweetreef]

looks like a keyhole limpet to me they are not bad..

 

[kimkissyfish]

Boy the fingernail looking things are scary.. Looks like when my cat puts out his nails..
Kim

 

[doboy]

The fingernail looking things are just the antennae that were pointing down at the time. It may be a limpet, as it has a pink and white frilly edge around the base (foot). I think hitchikers are the coolest!