I’m reading Dave Weigel’s brilliant history of prog rock, The Show That Never Ends. One of the earliest prog bands were the Soft Machine who took their name from the title of a book by beat generation icon William S. Burroughs.
The cover of their eponymous 1968 debut album had moving parts as described at Discogs:
Circular cut-out in sleeve, revealing rotating ‘clockwork image’ card insert- through which the band members can be viewed on a further inserted full-color backing sheet.
The older brother of a friend of mine had the LP. I recall messing about with it much to his displeasure. Kids do the darndest things.
Here’s the cover:
Here’s the gatefold featuring the band and a woman’s butt:
Here’s the whole damn LP. Despite the blank look, if you click on play, it, well, plays;