I dont know what cats you have… or even what I have lol.
But they’re smart contract tokens .
If you’ve bought none they are prob the free ones that were awarded for minting a block .
If so they can / will be used for savings on chia merch.
I’ve not heard of a secondary mkt, other than on this forum, someone released their own cats, and does battles / races i believe, and they allowed you to swap other cats for their cats to compete .