A "rare" lava-dome fountain spews lava in Hawaii on October 11, 1969. (J.B. Judd/USGS)
A red-hot bubble was caught on camera spewing out steaming hot lava 65 feet in the air -- and the Internet wants to know more.
The United States Geological Survey (USGS) shared the picture on "Throwback Thursday" last week to highlight a "rare" lava-dome fountain that was spotted in Hawaii on October 11, 1969.
"Dome fountain of episode 10, October 10–13, 1969, eruption of Kilauea Volcano," USGS tweeted. "Symmetrical dome fountains such as this are rare."
Lava domes -- or volcanic domes -- vary in size and shape. They can reach up to 1,640 feet high, but typically stay within ranges of 30 to 320 feet, according to the USGS.
They're also pretty common. They're formed by viscous (gooey) magma that piles up around the opening of the volvano, also known as the "vent," according to research compiled by Oregon State.
Dome fountain of episode 10, October 10–13, 1969, eruption of Kilauea Volcano. This dome fountain is about 20 m (65 ft) high. Symmetrical dome fountains such as this are rare. #Tbt #HI @Volcanoes_NPS pic.twitter.com/sKSQaVINKs— USGS (@USGS) March 29, 2018
"Like lava flows, they typically do not have enough gas or pressure to erupt explosively, although they may sometimes be preceded or followed by explosive activity," Oregon State explained in a blog post. "However, unlike lava flows, the lava that forms domes is often to thick and sticky to flow very far, and thus instead pile up thick and high around the vent."
This 1969 dome developed during the eruption of Mauna Ulu -- a volcanic cone in the eastern rift zone of the active Kīlauea volcano, the youngest on the island. Lava flowed fairly consistently in the location from May 24, 1969 to July 22, 1974.
"[It was] the longest-lasting and most voluminous eruption on Kīlauea's flank in at least 2200 years," according to USGS, noting that the eruption stretched a total of 1,774 days.
Over that time period, a shocking 350 million cubic meters of lava was produced. That's enough to fill "140,000 Olympic-size swimming pools," LiveScience noted.
But Mauna Ulu's record-long eruption has since been beat.
"[It was] the longest-lasting and most voluminous eruption on Kīlauea's flank in at least 2200 years."- USGS
Pu‘u ‘Ō‘ō, another volcanic cone on Kīlauea's east rift, has been pouring out lava for the past 35 years, starting in 1983.
"[It] ranks as the longest and most voluminous known outpouring of lava from Kīlauea Volcano's East Rift Zone in more than 500 years," USGS says. "Lava fountains and flows have profoundly altered the landscape and repeatedly challenged residents with lava inundation."
While Pu‘u ‘Ō‘ō is impressive, it's still overshadowed by Mauna Ulu, as the location of that volcanic cone is more easily seen.
"The Mauna Ulu eruption was more accessible to the public, with a viewing platform established at one point to observe a lava lake in the crater," USGS said.
The sight has certainly wowed the Internet, with hundreds liking the image and several commenting on the photo on Twitter.
"I had no idea...very sci-fi!" one user wrote.
"This is so sexy," another added.