Moles have polydactyl forepaws; each has an extra thumb (also known as a prepollex) next to the regular thumb.

I wished I were a forest ape; then I would have come equipped with a couple of extra thumbs.

It's as if he has just noticed an extra thumb.

Its hands had only three fingers, but each had been given an extra thumb where a man would have had his little finger.

Bone abnormalities in the hands include malformed or absent thumbs, an extra thumb, or a thumb that looks like a finger.

Other symptoms included an extra big toe and an extra thumb (6).

Henry was born with an extra thumb on his right hand and a serious heart defect that would require surgery to fix.

A mole has an extra thumb.

Len Horovitz, the doctor, had an extra thumb at birth and had to have it removed.

Grasping the man's hands, and having his grasped by those extra thumbs, brought back memories of his last visit.