Cordyceps is a genus of ascomycete fungi,the most famous of which is the vegetable caterpillar— Cordyceps sinensis. All Cordyceps speciesare parasitic, mainly on insects and otherarthropods; a few are parasitic on other fungi. Themycelium invades and eventually replaces the host tissue,while the fruiting body may be cylindrical, branched, or ofvery complex shape.
en.wikipedia.org/wiki/Cordyceps