Fibonaccus thadalii
As populations of Fibonaccus spinensis expanded competition became more intense. While the ancestors of Fibonaccus necrophageus became dedicated scavengers; a distinct population of Fibonaccus spinensis solved the problem of competition changing both lifestyle and anatomy, by returning to the water.
10.16 cm-12.7cm long
Originated in zones C and C1
Living in the shallows and along the beaches of Zone C1, Fibonaccus thadalii underwent some major changes to become semi-aquatic. The rudimentary lung became less useful underwater. They switched to primarily relying on cutaneous respiration and small gills. Their digestive systems still consist of a crop to break down organic matter before passing through the rest of the digestive system as water and salts are reabsorbed.
The species is ecologically similar to their ancestor, feeding on detritus, carrion, and the roots of Scrutitatus lamabratus while using their simple eyes to detect dangers such as Amfivioslontus lutosquama and Xenoslontus quadrambiguus. Their shells and bodies became duller and developed camouflaging patterns, with a pinkish brown shell and a blueish grey body with a tan underside; the shells also have slight shades of dark brown on the top, while the body patterns of spots and stripes are more a dark grayish-red, to reduce detection. If they do get spotted they will rely on their shells as a defensive barrier until the attackers lose interest.
Much like F. spinensis, F. thadalii devours the roots of plorts (specifically S. lamabratus of Zone C1) in order to get calcium for their shells, they will also consume sand and tarate bones as a supplement. They feed secondarily on the several species of Taxonophytes in the zone that grow in the shallows, such as Crooksoluis amfivios but this is only when other food is unavailable.
Much their their ancestor, F. thadalii are hermaphroditic, capable of self-fertilization when a mate is absent. Once they lay their 20-30 eggs, they leave them alone to develop which takes about a month. Juveniles rely move heavily on their skin and gills to extract oxygen and as such don’t go onto land until they become mature adults.