She is extremely similar to Squidward's temporary snail "Snellie" in the episode, "The Great Snail Race" and Mary from "Gary in Love." It is unknown whether Mrs. Puff's Snail is Snellie or Mary herself, a different snail but with the same body color and shell color, a twin to Snellie or Mary, or if it is just a coincidence.
Squidward must not have given Snellie to Mrs. Puff because Mrs. Puff claimed to have had her since she was a little girl, though that's almost practically impossible for her to have lived that long. But she wasn't seen in another episode. Besides, Snellie has smaller, darker blue eyes than Mrs. Puff's snail.