[3] In 1881, Petter Karsten included it as one of the original three species in his newly circumscribed genus Phellodon.

[5] The grey tooth is a small to medium-sized fungus with a leathery or corky fruiting body.

It may look like a convoluted single fruiting body but in fact each part has a blackish stem, and several caps can fuse together.

The cap tends to be concentrically zoned with a reddish-brown to blackish-brown centre and a pale edge.

In the British Isles it is associated with various trees including oak, beech, sweet chestnut, birch, Scots pine and spruce.