Mm...I had ramshorns that liked to eat my red lotus, too. Its the only snail I ever saw donig it and they didn't do it to other plants. In fact, I just realized I haven't had those snails since getting rid of the lotus! Odd.
Oh they enjoy the crypts too....The crypt is cheap though compared to the lotus...I have tried everything to rid my tank of them, but they just keep comming out of the woodwork.
I didnt have a problem with them eating plants for months...There is some algae growing on the crypt right now and they dont seem to stop at eating the algae...Perfectly healthy leaves have huge holes in them now.