To ask what this is?

[DrSeussPHD]

Found it on top of my 90s fireplace. House is a repossession and I've just moved in.

I've now broken the end of it so it had more full holes originally.

Any ideas?

What material and how big are those holes - too small for a hamster toy? Or was it actually part of the fireplace?

Something breakable (so not metal) that's clearly been burned on the fireplace. Holes the size of a 2 pence coin.

How big is it? Looks like some kind of spanner/socket thing. Like those teeth at the bottom are supposed to key into something

Those teeth are where I broke it! They should be fully formed holes!

Pure guess, an old fireplace exhaust pipe? - The holes would be to dissipate the heat...