From
here seems like Slimcoin has been listed on hoo.com, SLM/USDT pair, but if I go to the site I'm not seeing SLM there.
It is an old info. You can see price of SLM 3 dollars, it was once upon a time

Yep, seems like there used to be this page on their site:
https://hoo.com/spot/slm-usdt, but it's not available anymore.