Armored
Literally eats rocks. All the time.
Created as a solution to the growing pollution problem, as they will snack on plastics and the like as well, cleaning up the messes people have made very easily. Ended up being way more friendly than scientists expected them to be, so much so that they were released to the general public as “pets” of sorts.
Perhaps the rarer ones stem from those who the government sent to less carefully watched places (ie Chernobyl puppies or those that were dropped literally into landfills without any sort of stone to supplement the trash diet)
The “tusks” and extra long mouth work to help them scoop up their food way better.
-- now includes nursery lines --