Creab Shell

Creab shells have split from the crystank shell. They live in close symbiosis with the creab walker, which provides them with mobility and a source of nutrients. The two creab shells present on each creab walker are actually parts of a single organism. They are connected by thin root threads which weave through the creab walker’s body. The two shells are distinct in form and function, the head shell is the only one with eyes while the tail shell contains their reproductive system. Differentiation between head and tail shells is caused by chemical signals produced by the creab walker. In the absence of these signals they would form a simple shell lacking eyes or jelly production capabilities. Like their ancestor they have multiple simple eyes. These eyes produce electrochemical signals which are meaningless to the creab shells but are received and interpreted by the creab walker.

Creab shell’s reproduction is largely asexual. After their symbiont mates the creab shell will begin producing a gelatinous syrup laden with spores. This jelly is then spread across the freshly laid eggs. If nothing disturbs the eggs the spores will eventually germinate. Freshly germinated spores grow into a network of hyphae like roots which feed on the jelly. During this period if hyphae of different mating types meet they will fuse and undergo conjunction. Mating type is determined by a single gene with three codominant alleles resulting in six phenotypes. If the jelly mass has been eaten by a frugivore the spores can still germinate in the feces. This not only allows for greater dispersal but also increases the odds that spores of multiple mating types will be present in close proximity.

Eventually this mycelial mat will grow hyphae into the nearby creab walker eggs. These buds grow along the dorsal mid-line of the creab walker as a thin, root-like structure and detach from the main mass shortly before the eggs hatch. This central root will produce several side branches as it grows, the exact placement and size of which vary between individuals. Shortly after the creab walker hatches it will grow the two external shells out from the ready made openings in the walker's exoskeleton. As they age the shells will grow supplemental roots to further anchor themselves and facilitate nutrient transfer.