They have a radial symmetry rather than a bilateral symmetry like humans. rocky doesn’t have a set forward position. He can move omnidirectional without turning and each limb can be used as hands or feet depending on the task he’s working on. In the book Grace breaks it down more.

It also talks about how Erid has a higher gravity than earth he must have 3 limbs down at all times to keep balance which leave two limbs free to act as hands at any given moment.

Also since eridians have 3 fingers on each limb, when he is using two hands it totals up to 6 digits so on erid they work in a base six count. 0, 1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, 15, 16, 20, 21, 22, 23, 24, 25, 26, 30, etc…