Tiny mouse-inspired creatures you clone from earth and adapted to this planet. As much as on Earth, these critters are mainly used in science research. Its not required but if you add them in your science recipes, it will improve the output of them. Ive heard some animals also love to have that special delicatessen on their menu. They don't require cages, but their mechanics are a bit different. You can breed the studs which will be in your building breeding and the regular cottonguts which you can use. They are different and have their purposes. A good thing about cottonguts is they breed a lot, so its easy to have many. But extract good amounts of meat, brains, guts etc from them may not be a thing since you probably will need many due their size.