A dark, oblate thing drifts serenely on a surging river of lava , apparently immune to the immense heat and kinetic energy around it. Slowly, it trundles forward until, just in front of the camera, its prow reaches a deep riverbed. There, as if indulging in the display for the sake of the viewer, the black berg cracks open, lewdly spilling its hot, glowing guts. Red and warmed-over and satisfied, it sits in its own goop for a few moments, briefly damming up the flow behind it before proceeding onward downriver in its slow, diabolical way. [Photos: Fiery Lava from Kilauea Volcano Erupts on Hawaii's Big Island]
That stunning video was captured in Hawaii alongside "fissure no. 8," one of the rapid lava flows to emerge from the ongoing Kilauea Volcano eruption. Ikaika Marzo, a local community activist, captured the video and shared it with Hawaii News Now. Hawaii News Now reporter shared it on Twitter, where it went viral:
#LeilaniEstatesEruption #KilaueaVolcano LATEST: #IkaikaMarzo captures the phenomena that USGS has named a “lava boat”. Watch as it makes its way down the #Fissure8 lava river in Kapoho and then breaks apart https://t.co/66DxdlXUzZ @HawaiiNewsNow #HINews pic.twitter.com/bAQK1uYyJh— Mileka Lincoln (@MilekaLincoln) June 28, 2018
Hawaii News Now's report on the strange formation states that U.S. Geological Survey (USGS) researchers said the object was an "accretionary lava ball." A website created by San Diego State University (SDSU)'s geology department describes accretionary lava balls as objects that form when a hard piece of of solid rock starts to roll along the surface of a flow. It grows as surrounding lava sticks to the hard core in a spiral pattern "much like snow sticks to a rolling snowball."
When cracked open, they reveal a spiral structure to the rock, according to SDSU. Typically, such lava balls range from a few inches to 10 feet wide, SDSU said.
It's not clear from the video just how large this lava ball was, but it does appear to be larger than 10 feet. Live Science reached out to USGS with follow-up questions about both this lava ball and the observed emergence of lava balls in general from this eruption, but several USGS researchers did not return requests for comment.
Originally published on Live Science.