cyprinodon diabolis
as a birdwatcher i almost feel obligated to share a freaky ass bird as my answer to this month's bear carnival, but in a way it feels a like a bit of a cop out to Me personally, so i'm going to go with my other answer... the devils hole pupfish!
i genuinely can't remember how i learned about this fish, but it is one of the few animals i have linked on my outdated wikipedia profile archive of cool articles. i do recall being really fascinated with it because its natural range is limited to literally only one location: devils hole, nevada.
of course, being confined to a single geothermal pool makes it so that this fish is constantly at risk of extinction, as any sort of changes to their extremely fragile ecosystem will result in multiple pupfish dying. their habitat is so small that their mature population rarely goes over 100. to make matters worse, they are also currently being predated by a species of diving beetle that somehow introduced itself in the 2000s.
as a result, there have been multiple (mostly) unsuccessful attempts to breed a population outside of devils hole, with the very first attempt being made in the 1960s. i am, however, more than happy to inform you that the most recent attempt made some time in the early 2010s was a successful one and is still an ongoing effort.
there's not much else i can tell you that isn't already mentioned on wikipedia, so if you're curious to learn more about this tiny, 30mm fish, i'd like to redirect you to the first link on this post. there are other lesser-known pupfish that are similarly endangered you can find out about!
this is a submission to this month's bear carnival, "your favorite unconventional animal" by oracle of sages!