wataugachicken said:the common ones will get about an inch, but if you buy colombian ramshorns which are gold or brown/gold striped, they can get to 2-2 1/2 inches in diameter. they aren't the random stragglers you find in planted tanks. very neat to watch, and will crawl around on your hand in the tank if you are patient. of course, i don't let them do it for long - i don't know if they will bite and i don't want to find out.
No teeth, just a large pad/"tongue" which they use to scrape the glass with...I play with mine too, they do tickle, don't they?