Look what the cat's dragged in!

Interesting info from * butterandjam*. I didn’t realise they were so aggressive. There was a roadkill one that lay on the side of the road for ages near us.

Maybe a pine marten?

I'd be very surprised of a cat (or even a fox) would win a fight with feral mink.

We used to get them in the chicken house (where they would kill everything). The first time this happened I rang the local chemist asking to buy some strychnine. There was a kind of strangled cough and he replied " No, Madam, you can't. You need a gamekeeper". The gamekeeper's first words were " Always make a lot of noise before entering your chicken house; trust me you do NOT want to interrupt or accidentally corner a mink. They are absolutely fearless and very dangerous".

I once saw my three large dogs and killer cat corner a stoat, and stoat won hands down Stoats are small terrorists; this one used to come in the open back door to steal from their food dishes. It was absolutely brazen, no fear of me whatever.

Years ago our hunter tabby brought in something just the same from the woods behind our garden. We thought it was a mink tail.
We had an array of gifts from him: baby pheasants, live bunnies, lizards, birds, frozen fish fillets on Fridays and a turkey carcass through the open top bathroom window while I was in the bath beneath!
We never found out who the fish belonged to!

They look a bit like woolly caterpillars, but the fur on yours is very silky and long?
And you say there's skin underneath.
Weird.

No cat flap here, our cat asks to be let out or in ! Had a few cats but never a cat flap!

No idea about the fur but our cats manage to lose collars. We now have a cat flap that works on chips implanted under their skin.

Could it be bits from a wild Mink that has been killed by a fox?