Amadou is a spongy material derived from the skin of mushrooms. The Fomes fomentarius*, which you probably know better under the name tinder fungus' or 'horse hoof mushroom', grows especially well on pine and spruce wood. It's quite common in Eastern Europe, such as Hungary and Bulgaria. The mushroom has been used for centuries as tinder to carry fire and light your evening fire. The name that is often used is therefore Amadou tinder.
Amadou is widely used in sport fishing today. When the skin of the mushroom is dried, you get a kind of substance in which anglers store their (fake) flies. But because of the resilient properties and the brown pattern, Amadou is very reminiscent of leather. That is why De KiemKamer is exploring the possibilities of using it as an alternative to animal leather.
As part of our Celium project, we are currently conducting trials with watch straps. This is quite a challenge, because these straps are under enormous stress, like no other leather. But the first tests are very hopeful. The starting point is and remains 'stronger leather without additions or chemical treatments'.
* You can read more about this mushroom on the WikiPedia page.