If you go to the Paris Zoological Park, you’ll come across a creature unlike any other. It’s not an animal, but rather, a sort of yellow blob that looks like a living pile of old silly string with a powerful hunger for fungus.

As you can imagine, scientists have had a hard time classifying such an organism. It looks like a fungus, yet moves like an animal. It has no brain, yet can “learn” to navigate complex mazes in a few hours on its curious quest for food. What is this thing?

Technically, it’s called a slime mold (aka, Physarum polycephalum) — a single-celled organism capable of growing up to square meters in size, though most specimens don’t grow beyond a few square centimeters or inches. They’re found all over the world, usually on the undersides of leaves and logs, where they like to hunt fungi and bacteria.

In the lab, however, the molds have a hunger for oatmeal, and that has allowed researchers to unlock their weird growth potential. To capture food, slime molds stretch out long veins of goo that can squiggle around obstacles or through mazes with surprising efficiency.

In one 2010 study, scientists laid out dollops of oatmeal in a pattern representing Tokyo and the 36 surrounding towns. When let loose to feed, the slime mold branched out in a network similar to Tokyo’s existing train system, connecting the food piles with impressive efficiency. But wait, it gets weirder.

Other studies have shown that slime molds can actually follow their own slime trails back to a food source for subsequent feedings, suggesting this brainless organism has a sort of spatial memory and problem-solving prowess. When two or more slime molds merge together, they can share what they’ve learned and continue finding the most efficient path to food.

It’s certainly a mystery of nature, one that you can now see in all its glory in Paris. And if you can’t just pop into Paris, here’s a video explaining all you need to know about this yellow blob.