What is an Amadou Patch used for in fly fishing?

Amadou is a fungi that is both spongy and flammable substance. It's amazing ability to absorb water has secured it's use in fly fishing, to dry out dry flies.

An Amadou patch can be used to quickly remove water from the dry fly. Placing a fly within the Amadou patch and giving it a gental squeeze will absorb water on the fly, allowing dry flies to regain their buoyancy to float on top of the surface film again, extending the useful life of the fly.