Claudette the confused crab from Cornwall has escaped the cooking pot after growing an extra claw.
A fisherman caught the 20cm (7.8in) edible crab near the Cornish coast, and realising it was a bit unusual, decided to hand it into Newquay aquarium.
That saved the crab, named Claudette, from becoming someone's dinner, and instead it will live at the aquarium.
Manager David Waines said finding a crab with a third fully-formed pincer is "incredibly rare".
Mr Waines said: "I have only seen this once before. It's obviously some sort of genetic mutation."
Crabs are able to grow new legs or claws if they get lost or damaged in a fight.
It's thought Claudette may have got a bit confused and instead of growing a replacement claw grew a third one to go with the two she already had.