[dfxm12]

Droste? Recursion? I'm sorry, but I'm contractually obligated to drop this link because it is hot cocoa season where I'm at in the world, and after looking at my box of Droste the other night, this is in the front of my mind: https://en.wikipedia.org/wiki/Droste_effect

[block_dagger]

Also see: Land O'Lakes, Morton Salt, and Cracker Jack.

[dekhn]

See also: https://www.google.com/search?q=recursion

[lgas]

Also Pink Floyd's Ummagumma album cover.

[unit149]

Look at Loveless: two amps, facing one another with a microphone embedded in between. Shields did not use any pedals for the album. Audio is recursively transformed in a synthesis of feedback loops.