another snail

ok well without a picture i know it is hard to tell me what it is, i have two snails in my tank. they are oblong shell size, and are "puppy dog pink" in color. any help would be nice. if they are bad or good or what.
thanks
 
ok well it is actually it is one that slides along the wall. it is always along the front of the glass and never moves to the other sides, so i can usually only see the shell while i look at the side of the tank.
 
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