Aah, those pics are useful
It's a worked bit of masonry. The first pic shows a recess that would have taken an iron or lead masonry clamp to fix it to the next stone.
At some stage it got broken, you can see it's not a perfect fit and there's a bit of weathering on the break.
Then someone decided to carve the figure and in all probability it was put back together and used in the building.
It's probably a form of ritual protection, this was quite common in buildings, dark spaces had to be protected against evil spirits. Masons would carve things never intended to be seen by anyone, i've come across an elaborate cat's head corbel that was supporting the main beam on a church tower.
Only folk working on the church would ever get to see it.
Other offerings were shoes, mummified animals and used items such as spoons and clothes.
It's worth a lot of money to the right collector
