What Can You Do? (Patreon)

Ongoing adventures here:

https://www.webtoons.com/en/challenge/the-talon-of-wisdom/list?title_no=485558

There's also a bit of lore on the bearlk:

Our heroes are currently in the country of Callahay, in the province of Springdale. The bearlk lives specifically in these parts where many of the mountains are extinct volcanoes. The region has plentiful deposits of igneous stones and valuable ores, including andesite and cassiterite, from which can be harvested phosphorous and tin, respectively. The tin is regarded as one of the more important exports, sold to New Callahay in the northwest, to be smelted with their copper to make bronze.

Bearlks are slightly magical creatures, but mainly just eat a little bit of andesite and cassiterite to store in a sort of "bear gizzard". When agitated, with a little magic and the andesite  phosphorous, they heat the tin to molten temperatures and vomit it at their foes. Bearlks are fairly rare, but find the ore stocks of the local minings to be easy pickings, and so they are a major nuisance to the mining towns of Springdale. Bearlks don't usually need to eat these minerals often, so the typical strategy is to go inside, let them take a bit of the lower quality stuff, and wait for them to move along. Very few people would provoke one on purpose.

As with my "Fantasypunk" idea, feel free to use the concept in your own games! Break out of that monster manual and surprise your players with something that will make them mad because it's not in the manual and your homebrew is killing them.