Shelpads

The cell wall on part of the shelpad genus is greatly expanded and thickened. This part of the cell wall functions like the shell of a turtle. Since the shelpad's nucleus is within the part of its body protected by the shell, it is plausible that the shell offers the organism protection against viral attack. The shell may also protect the shelpad from water loss in highly saline areas.

The shell itself is fortified by the polysaccharide pectin. As pectin is commonly used as a thickening agent in jams and jellies, when enough shelpads die in an enclosed area, the water becomes viscous and jelly-like in consistency. (Such enclosed areas are normally puddles or small tide pools.) The cytoskeleton is also reinforced with pectin, though to a more limited extent. The cytoskeletal reinforcement allows the shelpad to reach large sizes. (by padler standards)

While shelpads have a global distribution, they occur in the greatest levels in stagnant waters. Only a few strains live in freshwater; most live in saltwater. Freshwater strains have a smaller size range than saltwater strains, and proportionally less pectin in their shells. Some puddles in salt swamps are so saturated with dead shelpads that the puddle essentially turns into dessert gelatin, allowing small organisms to walk on the surface.

Shelpads are frequently picked up in storms. The storm picks them up and drops them inland. On rare occasions, storms pick up so many shelpads that the shelpads' dead bodies make the raindrops jellylike. It's not presently known how this affects precipitation. Starving herbivorous organisms have a fondness for "shelpad gelatin." The pectin of shelpads is a soluble dietary fiber, and thus drinking shelpad-rich water soothes their hunger. Though their pectin shells protect them from viral attack, they do not protect them from filter-feeders. They are eaten as would any similarly-sized organism. Bubblerorms are an especially voracious predator.