Children in a nursery were shocked when they spotted a three-headed frog hopping in their garden.
The creature - which has six legs - has stunned a BBC wildlife expert who said it could be an early warning of environmental problems.
Laura Pepper, from the Green Umbrella nursery in Weston-super-Mare, said: "We thought it was three frogs huddled together at first.
"It is very strange. The children couldn't believe it."
Mike Dilger, from the BBC Natural History Unit, said: "I have never seen anything like this.
"Frogs are primitive animals - so the occasional extra toe is not that unusual. But this is very unusual."
All the creature's eyes and legs appear to function normally, but it is not known whether it eats using all three of its mouths.
The amphibian was kept in a container for several hours but hopped away later while nursery staff were showing it to curious parents.