Fertile surface usually a layer of vertical tubes, of which the mouths are visible as pores on the underside of the cap or shelf. Fruiting bodies usually tougher or harder than the "normal" gilled mushrooms, being leathery, corky, or woody. But they can be quite tender while actively growing
Once grown, they do not decay easily, remaining on the substrate for months or years
They often grow on wood, although a few are terrestrial (even those are usually growing on buried wood) Fruiting body is usually a flat shelf, or hoof-shaped, protruding directly from the substrate, although sometimes it may have a short stalk.
Some forms never grow away from the substrate at all, so that all that is visible of the fruiting body are the pores.
Sometimes the pores are so minute that the fertile surface seems solid, until you look closely
It's possible to mistake them for boletes; but their flesh is tougher, they lack the deepcolors that some boletes have, and their tubes do not separate easily from the cap. Their stem is not black and rooting, as in Polyporus radicatus. Their coloration is similar to a young Bondarzewia, which could be about the same size at that stage in its development, but a Bondarzewia is likely to be much more irregularly shaped at that point
Cap grey, brownish or blackish, sometimes slightly scaly; except for the spores, this is the way to tell it from Albatrellus, as no Albatrellusspecies have these colors (although one species is dark slate blue)
Cap and stalk some dingy combination of grey, brownish or blackish, perhaps with tinges of olive, bluish or other faint colors; sometimes with minute scales or fibers Cap almost round, often virgate Flesh white to grey, tinged with various colors like cap Taste sometimes bitter Odor absent when fresh, sweet to spicy when dried
brown, furry, wrinkled, irregular in shape; often clustered, imbricate, or intergrown with one another; pore surface starts out buff but ages dark brown