In 1949—long before the sweet little guys were making our floors dust-free—a British neurophysiologist and roboticist named Dr. William Grey Walter invented a mini-gang of early autonomous electronic robots; the Roomba's long-lost, distant great-grand-relatives.
This was a concept that Walter seemed to embrace; he called them his "tortoises" and named his them Elsie and Elmer (awww!). After explaining about how they function—exactly as if they had a two-cell nervous system—and how they "see"—out of a photoelectric cell that rotates above their metal bodies—Elsie's batteries ebb low she "runs back to her kennel" to recharge.
Apart from their (abundant) retro charm, these gizmos represent what was a significant step in the study of brain function and neural connections. Plus—c'mon, they're just delightful.