Mysterious structure

Mysterious structure

Credit: Troy Alexander / Tambopata Research Center

While volunteering in the Peruvian Amazon, graduate student Troy Alexander discovered a strange web formation underneath a tarp.

Circle and spires

Circle and spires

Credit: Troy Alexander / Tambopata Research Center

The formation, about 0.8 inches (2 centimeters) across, had a strange spire in the middle encircled by picket-fence like posts.

Slime mold?

Slime mold?

Credit: Image courtesy of Audrey Dussutour

Experts guessed it could have been a slime mold, a structure made by moths, or a defense made by spiders, but everyone was stumped.

Return to the scene

Return to the scene

Credit: Jeff Cremer / Perunature.com

So several months later, a team of researchers returned to the site to study the structures. After putting them in a glass, they found baby spiders hatched from the strange structures.

Spider eggs

Spider eggs

Credit: Jeff Cremer / Perunature.com

The mystery was solved: The web towers were used for spider eggs, from which tiny, less than 1 mm spiderlings emerged.

Still unknown

Still unknown

Credit: Jeff Cremer / Perunature.com

But it's still not clear what species of spider made the webs or what the picket-fence circle is for.

Ant defense?

Ant defense?

Credit: Jeff Cremer / Perunature.com

One possibility is that the fence is a defense against ant invaders eating or damaging the eggs, or the spikes lure mites as tasty snacks for the hatchlings.