Forest Slider
The forest slider is a docile tripedalien from the Pocket Forests of Darwin IV, possibly closely related to the keeled grove-back due to its growth cycle.

These creatures can be seen shambling along in the pocket forests. They can sniff the air with their purple, hyperextended oral tubes. Parents take good care of their striped offspring. Between an adult and a juvenile there is a discrepancy both in size and in the number of limbs. The adult possesses only two legs and a skid, but sometimes there is a dangling, wrinkled flap of tissue where the juvenile's single hind leg is to be found. They can be easily startled by noises produced by other life forms, even those that pose no true threat. At one point the forest slider will have the "deformed" leg scraped completely off, and is unperturbed by its loss. Amazingly, there is no wound, concluding that the discarded growth had been the neotonous remains of a limb used during the creature's early life, before it gained the control of its pronged pelvic skid.

Forest Slider Shrivel

Forest sliders seem genuinely unperturbed by the loss of their hind limbs. In fact, Barlowe noticed an increase in mobility once the hind legs are shed. While the body may appear ponderous, it is actually lightweight and can be lifted from the ground to execute rapid turns.

Forest sliders will sometimes drink copiously midway out in a stream, wet sides heaving as it sucks down water. Parents shall emit warning pings as their young hobble after them, approaching the slick rocks of a bank. Warned, the juvenile goes no further until their parents permit them. They will drink water for a quarter of an hour.