If nothing else, Ditko was the master of the 'Less is More' approach. While some of his early Charlton horror covers are loaded with detail, his covers from the late 50s onwards often focused more on the core concept and/or design. Th cover to Mysteries of Unexplored Worlds #3 (April, 1957) is an early example of this approach. It is a very simple set-up, and will certainly grab a young reader's attention while staying well within the parameters of the Comics Code. While may of Ditko's other covers on this title have far greater detail, they are no necessarily any more effective. By the 70s, of course, Ditko would be selling very simplistic covers to Charlton. It's hard to know how much was influenced by an internal artistic shift, and how much had to do with Charlton's lower rates. In any case, this is an interesting step in his evolution as an artist.