ID Help....Does anyone know what this is?

[snooky]

They are growing on all my rocks....is it harmful to the tank? What will eat these? Thanx

 

[spanko]

Looks like vermetid snail to me.

 

[snooky]

one other trait about this is, when you agitate the water (water change....clean glass etc....) a fine mucous is emitted from the top of the object

 

[spanko]

Go to the first link that comes up here,
http://lmgtfy.com/?q=Snails+That+Wor...Way+Into+Tanks