These type of enemies can only be found on Frozen Wasteland planet type (included in the randomizer). Compared to the ones that the Hero encounter on Eta Astropelecae, they can be thawed by dealing damage on them. Thawed chicks/chickens move randomly on the screen, the same way as enemies escaped from eggs. These are weak against fire-based weapons, of-course.
Hero quip: Hmmm snowgrave