The Outslay is a symbiotic Bydo associated with Gomander; where a pilot will find one, the other won't be far. Often, pilots will encounter the Outslay first. Seeing as how the Gomander is an immobile creature, the Outslay is responsible for defense of the large Bydo and does so by spraying Bydo Shots around the body; each segment can do this. The creature is invulnerable in most missions, but the body can be easily damaged, rendering it incapable of ranged attacks. Diving into and emerging from Gomander will regenerate the body parts. Inattentive pilots who cannot predict the creature's flight pattern will quickly fall prey to it.
Covered with a tough shell, these creatures guard the Cyst.
It's referred to as Worm here and Insuloo in the Game Boy port.
Outslay is encountered long before pilots see the inevitable Gomander.
The Outslay is a snake-like parasite that clings to the giant Bydo, Gomander. It lives off energy leaked from Gomander, returning it inside, where it again cycles to the outside. If the Gomander is killed, the Outslay will die too.
It's called the Enthrew in this mission. Much like the Force units, this creature is no longer invulnerable, though its extremely high hit points render it nearly so. True to the spirit of earlier encounters, commanders may find it easier to destroy the weaker Gomander counterpart.
B-Inthr Enthrew -Sentinel Morphon-
Parasitic organic machine said to be nearly indestructible. Circles the Gomander to act as its guard.