https://phys.org/news/2018-07-reveals-complex-math-worms-food.html

Think of the game "Hot or Cold?", says Zaslaver. "Imagine you're in a huge dark house and a chocolate cake has just been taken out of the oven. To find the cake, you'll probably sniff around to see what direction the cake scent is coming from and begin walking in that direction."

Turns out, worms employ this "Hot or Cold" computation in their search for food—but with an added twist. First, a neural cell picks up the scent of food and set the worm on a course. As long as the scent intensity keeps getting stronger, this neural cell will remain active and direct the worm to keep moving forward. Otherwise, it will instruct the worm to stop and look for a better path.