Shingled hedgehog or Devil's tooth

The cap is 5–15 cm across and up to 25–30 cm in big specimens, and fleshy. It starts convex with an inrolled margin, then flattens, often with a dip in the middle, and in old caps the centre can open right down into the hollow stem. The margin becomes wavy with age.

The surface is dry, pale brown, buff or greyish brown, and covered in coarse dark brown to purplish brown scales. They sit in rings like roof tiles and get bigger and more upturned towards the centre. Young caps can be very pale, pinkish grey with small dark triangular scales.

The cap is 4-10 cm across, convex at first, then flat and spreading, with an uneven, wavy edge and sometimes a crater-like dip in the centre. Young caps are white or cream, with red droplets of exudate on the porous surface. The surface is velvety-felty and rough. As it ages, the red drops dry up and the cap turns grey-brown to dark brown, with uneven lumpy outgrowths.

Instead of gills there are crowded spines 0.5–1.5 cm long, brittle and running slightly down the stem. They are greyish white or pale lilac grey when young, turning greyish brown and purplish brown as the spores ripen. The spine layer comes away easily from the cap flesh.

The spore print is brown, which separates it from the Hydnum hedgehogs with their white print.

The underside is covered in spines (small sharp teeth), typical of the genus Hydnellum. They're thin, 2-5 mm long, whitish at first, turning pinkish brown to purplish brown with age. The spore print is brown.

The stem is short and thick, 3–8 cm tall and 1.5–4 cm wide, central or slightly off-centre, often widening towards the base. It's whitish to pale brown and browns from the base upwards. It's smooth apart from traces of stunted spines at the top, becomes hollow with age, and has white mycelium at the base. There is no ring and no volva.

The stem base is pale, with no green, blue or black colour outside or in the cut flesh. That's the feature that separates it from the bitter tooth fungi.

The stem is 2-5 cm tall and 1-3 cm thick, short and coarse, and sometimes fused with its neighbours. It's red-brown to brown, with a velvety surface and no ring.

The flesh is whitish to pale brown and soft, turning greyish brown in old specimens. It doesn't change colour when cut. The taste is mild in young mushrooms and bitter in old ones.

The flesh is dense and corky, dark reddish brown, with darker and lighter concentric zones when cut. The taste is burning and bitter; the mushroom is impossible to eat.

Fresh mushrooms smell faint, of almost nothing. When fried or dried they develop a strong, spicy aroma, which is why the powder is prized as a seasoning.

A faint mealy or earthy smell. The taste is extremely hot, bitter and peppery: even the tiniest taste burns the tongue.