Crystal-Tears
Statistics depend on host.
Crystal-tears are produced by symbiotic microbes inhabiting tear ducts; some may inhabit scent or oil glands instead. When the host is at rest, they secrete a thick gel, which the host then spreads over its feathers, fur, or scales. This hardens to form a slightly pliable crystal, much as a spider's spinneret fluid hardens to form silk. Different varieties have different effect. Some are very restricted as to climate and species while others are more adaptable; some speculate that armadillos and pangolins are actually armored by species-specific varieties of crystal-tear.
The most elegant effects are to be found only in faerie-frequented lands or beyond the portals of the Dreamlands. Here, diverse creatures may be found which glimmer as if clothed in living gems. While "infection" of new creatures with stained-glassteel-like crystal armour is almost impossible without major majical assistance outside their native habitat, such beautiful creatures can maintain their crystal coverings indefinitely if given a diet high in silica and select other minerals.
Whether the change in appearance is to one of breathtaking stained-glass beauty or simply a granite-like micro-texture, the effect is an improvement in armor-class or toughness by 1-3 points, depending on how thick the crystalline layer is; un-fused feathers or fur increase by only one point, while fusing brings two points. (Yes, fused feathers do remain light enough and pliable enough for flight, although they look like scales.) Heavier armor, such as of an armadillo or crocodile, gives a full three-point improvement. Larger, giant-sized creatures, able to support greater weight, may gain thicker armors with greater protection values. Resistance to fire, electrical attack, and other side effects are also known. Only rarely do crystal-tears armors inhibit dexterity or agility.