This week I learned that while you may purchase automated snakes:
... your cat will still prefer the classic ball of yarn, especially if you make it wiggle like an automated snake.
However, the most important thing I learned was from a friend, who said cats should not play with yarn unattended. The yarn can get stuck on their tongue barbs, then they swallow the yarn. which proves fatal. (Though somehow the same thing wasn’t fatal to R. Crumb’s brother Maxim.)