The tiny hollow piece of volcanic glass (Photo: USGS)

One morning early in January,  the Halema’uma’u crater, in the Hawai’i Volcanoes National Park, had what the park called ”a small explosive event.” This can happen from time to time, when rocks on the crater’s rim heat up, fall in, and trigger an explosion that shoots bits of lava and volcanic rock fragments up into the sky. It looks like this:

Later that day, a geologist was walking the rim of the crater and collecting samples, when he found what he called “an incredibly curious thing,” the Honolulu Star-Advertiser reports. It was a tiny drop of lava, about a half an inch long, and it was completely hollow inside. 

“Nothing like this has been seen before,” the geologist, Tim Orr, told the Star-Advertiser. Volcanoes do often spit out tiny drops of lava that solidify into small pieces of volcanic glass–they’re called Pele’s tears. But they’re never hollow.

The scientists at the volcanic observatory aren’t quite sure how this little shell formed; it may have been an entirely different process than a Pele’s tear. If anything, it looks like it was a bubble of lava that somehow detached itself and solidified.

It’s also incredibly fragile: one wrong touch and it could disappear forever. 

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Every day, we highlight one newly lost or found object, curiosity or wonder. Discover something unusual or amazing? Tell us about it! Send your finds to [email protected].