Courtesy of the Autumn 2022 National Trust magazine

A tortoiseshell cat stone corbel at the bottom of the stairs at Knightshayes Court, Devon.

A "corbel" is, per wikipedia, a structural piece of stone, wood or metal jutting from a wall to carry a superincumbent weight, a type of bracket.

The magazine article says, of this one:

If you stand beneath the staircase galley at Knightshayes and crane upwards, you'll spot a strange creature with a cat's head and a tortoise's body seemingly emerging from the wall. It's a visual pun, a picture puzzle known as a 'rebus', and it represents a tortoise-shell cat.

Its designer, William Burges (1927--81), had a vivid creative imagination inspired by his passion for the art and architecture of the Middle Ages...

It's apparently 17 x 11 cm; I've been vaguely intending to share it with you all since I first skimmed the magazine a few months ago, but it's only today that my search terms have finally managed (indirectly) to point me toward the National Trust photolibrary!