Name that animal - round 8

Ayshela was correct that the Pippi-Longstockinged creature in round 7 was a Zedonk (image credit to EricaLucci). A zedonk is the offspring of a zebra stallion and a donkey mare; apparently other neologisms include zebrass, zebronkey, and zonkey. Mental Floss has a page showing other hybrids, including a very impressive zorse.

For round 8 I've inserted two photos above - a frog and a snail. That's the easy part. Now tell what they have in common (or if you can name them then that will show you know what characteristic they share).