Two kittens have been discovered with 18 extra toes between them.
Ned and Fred were handed in to the Gosport Town branch of Cats Protection in Hampshire.
Normally cats have five toes on their front paws and four on their rear, but Ned has an extra eight toes and his brother Fred has 10 extra.
Dr Andy Sparkes, from the Feline Advisory Bureau, said the four-month-old kittens were "very unusual" due to the large number of extra toes.
Cats Protection field veterinary officer Karen Hiestand said Fred's extra toes on his back paws as well as his front paws were also an "extreme case".
She added that the extra toes did not affect their health.
The kittens had come from a "multi-cat household" and arrived at the charity branch in a "poor condition".
They are still with the centre, but are due to be rehomed with a new owner in two weeks.
Cats with extra digits are known as polydactyl and usually have just one extra toe on each paw, but some can have two or three extra on each paw.