Cave sheep (SciiFii)

The cave sheep (Phasmatovis spelea), sometimes known as the wool-o'-wisp, is a species of wild sheep that originally did not exist, but has since been created by SciiFii and introduced throughout Eurasia and North America to help boost biodiversity. The closest living relative of the cave sheep is the domestic sheep (Ovis aries). Unlike other species of caprids (sheep, goats, etc), the cave sheep is extremely specialized for a nocturnal lifestyle, using caves and other subterranean tunnels to avoid predators and bad weather, venturing out only at night to graze, using its large sensitive eyes and ears as an adaptation to such low-light conditions. The highly reflective tapetum lucidum in the cave sheep's large eyes gives it excellent night vision, and also causes the "glowing" eyeshine effect. While in normal lighting, the cave sheep resembles a small sheep with an almost rabbit-like face, in deep darkness, its most unique adaptation becomes apparent, it glows in the dark. The glow isn't from the sheep itself, but from a bioluminescent fungus which grows within its fleece. This symbiotic arrangement gives the fungus plentiful food sources, feeding on and breaking down the constantly-growing wool. Meanwhile, the cave sheep gains its own faint natural light source even in the darkest regions of the cave system, aiding in navigation, along with a build-in hair-trimming system to prevent its fleece from growing too long and unwieldy. The cave sheep's fleece is a small ecosystem in itself, hosting various lice, ticks, mites, beetles, and moths along with the glowing fungus. Additionally, the presence of the fungus acts as an efficient predation deterrent, despite the glow making the cave sheep more conspicuous in the dark. Along with smelling and tasting foul, the fungal-weakened hair shafts of fleece break off really easily, and attacking predators are likely to end up with only a chunk of slimy wool in their grip. The conservation status of the cave sheep is Least Concern due to successful conservation efforts, the cave sheep's wide range and its tolerance to many of the human activities.