A house made of snot? It may be a yucky thought, but it’s also an underwater reality. Scientists say so-called “snot palaces” could one day benefit human construction—if scientists manage to crack the mucus-building code.

Tadpole-looking critters called giant larvaceans build vast yet delicate homes every day or so—all from mucus. The creatures inside these houses are small—the biggest are around four inches.

Larvaceans gather food by filtering water through their snotty houses. When the house gets clogged with debris, the animal simply builds a new one and discards the old. The house drifts to the seafloor where other animals eat it.

Kakani Katija is a bioengineer at Monterey Bay Aquarium Research Institute. She and her team use submarines, cameras, and lasers to study these creatures and their houses remotely. The structures are so delicate that researchers cannot easily study them in a lab.

Larvacean snot palaces aren’t simple. They’re often nearly transparent and flow all around the critter. Water passes through the house. Two chambers act as a maze for food that drifts in. These chambers resemble flexible dryer vent ducts. They direct food straight into the animal’s mouth.

The larvaceans’ houses are about 10 times bigger than the critters themselves, reaching more than three feet wide. Compared to the size of its inhabitant, that’s the equivalent of a five-story human house!

“They create these . . . houses by secreting mucus from cells on their heads,” Katija says, “and then expand those much like a balloon into the structures that we see.”

Katija’s team uses 3-D laser scan technology. Software models the inner workings of the structure. Then the scientists fly through the inner chambers of the snot palaces virtually. But they are far from understanding them.

Larvaceans “are like an alien life form, made almost entirely out of water, yet crafted with complexity and purpose,” says marine biologist Boris Worm. Worm’s choice of words shows he recognizes—whether knowingly or not—that complexity and function need a creator. It’s true. Fantastic creatures like this don’t just happen: The Lord God made them all.

Katija says of snot houses, “It could be the most kind of complex structure that an animal makes.” She and her team are working to solve the mysteries of snot houses. They hope someday to reproduce them. In the meantime, Katija believes engineers looking to build structures on the Moon could probably learn from Earth’s floating master builders.