The particular Beaver is patterned after a “ram’s head” Muff, so named because the pedal featured the now-seldom-used Electro-Harmonix ram’s head logo. This was a 1970s incarnation of the Muff circuit and is renowned for versatile, singing lead tone.
Taking its inspiration from the strange Snarling Dogs Mold Spore Wah, the Wilson Effect Mycelium features everything in that pedal EXCEPT the wah part. That's ok, the wah part was average at best, but the real meat-and-potatoes of the circuit is the wacked-out ring modulator that exists therein.
Kevin Wilson of Wilson Effects loves wahs. So much so, in fact, that the Wilson Signature Wah is modeled after not just a particular kind of wah, but after one particular Clyde McCoy signature wah that he himself owns.