The Gobbob is a prolifically-reproducing, semiaquatic, largely nocturnal organism of beaches, which sucks up tiny photosynthesizers from tidal pools or eats decaying flora that washes up on shore.
The Gobbob lives between the damp sand of the beach and the low-tide mark of the nearshore; only its larvae live farther out, though still in the shallow waters close to the beach.
Its epidermis is a little thicker and less watery, helping to protect itself from injury as it rolls around on land. Its ring-like lips contract around its mouth on land, reducing the amount of water it loses to evaporation. The thicker skin and development of blue skin pigments make it resistant to ultraviolet, and make it only slightly translucent. However, as it is not so resistant to ultraviolet as descendants of the Knightworm, it only moves in the evening, at night, and in the deep shade of tall flora.
The Gobbob lacks natural armor and weapons. It survives largely through camouflage in water, nocturnality, skittishness, alarm signals, switching between land and sea to evade predators, and sheer prolific numbers.
Its photoreceptors have developed into much bigger pigment-cup arrangements. Gobbobs can detect color and differences of shading, including shadows. While its lights are normally dormant, it flashes certain colors brightly and rapidly when attacked or even startled. This startles predators, and the strobing causes a chain reaction where other Gobbobs automatically try to escape and start strobing too. The Gobbob’s improved ability to detect direction helps it avoid obstacles as it rolls on land, though not very much (especially since it lives in dim to dark conditions).
Its fins are pretty stiff, functioning mostly like spokes or spurs. It navigates mainly by pushing off with its tail and awkwardly rolling from side to side. However, it can also move by pushing itself onto its mouth, sticking to the surface like a weak suction cup, and then weighting itself down on the other side with its tail.
If menaced by the Beach Arthrothere, it will rapidly roll towards the surf, where its predator cannot move so well. Its slow maneuvering around obstacles (such as Caltrop Crystals) mean that areas with particularly dense Caltrop Crystals are practically a minefield to it, while its predator finds it easier to navigate around the obstacles.
A separate set of colors is used to lure other Gobbobs closer to mate, whereupon they spawn into tide pools. At high tide, the tide pools are covered, and the larvae go to deeper, more food-rich (if more dangerous) waters close to the beach.
Due to its alcohol-producing symbiotes, Ribbon-Tailed Detriti, the Gobbob has a faint taste of alcohol.
In some ways, Gobbobs’ physiology is like a blend of a jellyfish and an octopus. Its more complex escape responses required a more advanced nervous system, though it is still technically brainless. Now, it has a nerve net, similar to that of a jellyfish. The net radiates out from the outer tissues of its stomach to below its epidermis, just above its lights, in a basket-weave-like pattern. (Diagram A) The nerves also coordinate the contraction of its lips on land: dead Gobbobs have wide-open mouths on land.
Its body has a system of pockets of air and water. It has twenty major pockets (five between each pair of lower fins), and sixteen minor pockets in its tail. (white spots, Diagram A) The system creates a hydrostatic skeleton in its tentacle-like tail, allowing for more complex movements than in its ancestor.
The muscles and support structures of its body are in a wheel-like arrangement. The outer walls of its stomach, above its first pair of fins, have bands of thickened, cartilage-like tissue. (Light blue, Diagram B) Between each band is a clump of muscle, attached to both the cartilage bands and the outer walls of the Gobbob's stomach.
Its yellowish, teardrop-shaped reproductive glands are nestled in membranes beneath cartilage-like "shelves" below its lower fins. It reproduces both through larval clones of itself and through gametes. It reproduces sexually when physiologically stressed. As cold temperatures stress it out, it reproduces exclusively sexually over the winter.