Slime molds are weird creatures. As simple (sometimes single-celled) organisms, they have to coordinate and cooperate in a swarm in order to get things done in the larger world. What's wild is that they succeed at complex tasks, forming structures based on simple rules in order to do things like finding food in a maze. (Or, better yet, finding the best route to get to the food and then ignoring all the other routes.) Whether you can call this behavior "intelligence" is debatable, but it's certainly impressive to watch!
There's a strong parallel between slime mold behavior and simple insect behavior (think: ant colonies), except that ants are substantially more complex as individuals. Check out this video from It's Okay To Be Smart for a deeper dive:
For more on slime molds, check out KQED's article that accompanies the Deep Look video.