dwellers of the moonlight.

The spongyll is a two dimensional, bosonic lifeform which feeds on neutrinos and can only exist in moonlight: at day it is too hot, and the artificial light of the anthroponemous settlements on La Arth is too harsh and of the wrong spectral character. They are close to transparent. Being of a bosonic nature, two spongylls may exist in the same space at the same time. At their smallest, each spongyll is about a square meter, though they can range in size from a square kilometer by attenuating their material. There is a degree of danger of being so attenuated, though: sudden light from thunderstorms or meteors or perhaps anthroponemic activity may kill an attenuated spongyll. For reasons that are inexplicable to the current crop of anthroponeme biologists, spongylls prefer cool air near areas of dense vegetation, and cloudless skies.

At day, or when the environment is not correct for them, they sporulate, forming neutrino sized spores which have a tendency to stick to the centromeres of treebark dwelling crustose lichens. In some places, though, where there are vast caverns or other dark spaces of appropriate humidity and flora, spongylls will overday and sleep: since these places are few in number (spongylls detest bat caves, and do generally sporulate if there's a batcave around), the population of spongylls that sleep rather than sporulate is rather small. 

The method of reproduction of spongylls is rather peculiar: rather than classical binary fission or sex, the spongylls reproduce by interference, as two spongylls can inhabit the same space at the same time: they set up a number of spongyll-eigenstates in the surrounding false-vacuum, and at the end of the reproduction cycle, either 3 or 7 spongylls are constructively interfered from the two original spongylls, which have now been resurrected as state-vectors amongst the new spongylls. It should be said that in this way, the spongyll represents a sort of state of miscible life: rather than the pure death, the spongyll population is a kind of way-station for spongylls from here to their. 

If the conditions are just right, and you know the right syllables (something like "na khra gad taw pru bo"), and the moonlight is streaming down, and you see a spongyll, hold your hand out and say that phrase. The spongyll will stretch square and center itself with your hand.