It’s the Carnyx, which Discover Magazine helpfully talked about a few months ago:
The carnyx was a terrifying instrument. Brandished in battle against Roman invaders, the Celtic horn was taller than a horse, resembled the head of a boar and produced “a harsh sound which suits the tumult of war,” in the words of one ancient historian. But Scottish archaeologists studying one of the most complete surviving examples — excavated from a bog in 1816 — wanted to actually hear it. So they commissioned metalsmith John Creed to craft a replica in bronze and brass. Four hundred hours of meticulous work, using Iron Age techniques, resulted in an instrument that would do a Celt proud.
And here it is:
Peeper, our stripey cat, hated it. Mayhem doesn’t seem to mind it so much. Here’s another sample by the same artist:
