Researchers discovered a pair of rare asphalt shooting "tar volcanoes" while searching for shipwrecks recently in the Gulf of Mexico.

The archaeologists and marine biologists were using underwater robots to explore three nearby shipwrecks believed to be pirate ships that sank over 200 years ago, according to a report by the Houston Chronicle.

 "They weren't shipwrecks, but two extrusions of asphalt onto the seafloor," said William Keeney, with the National Oceanic and Atmospheric Administration, according to NewsFix.com.

A video of the discovery can be found at the bottom of this article.

The formations were the first of their kind to be found in the northern Gulf, according to the newspaper.

They left behind solidified eruptions that the researchers nicknamed "tar lilies" because the eruptions were similar to petals.

"These are kind of unique, in that they've split open and formed a flower structure," said Keeney.

The volcanoes, which are approximately 20-feet-wide and 10-feet-high, are considered islands for life in the deep waters, located approximately 175 miles off the coast of Texas.

The volcanoes first looked like "man-made objects" on sonar readings, according to the researchers.

"The deep sea is normally very, very barren, it's practically a desert," said Thomas Heathman, a Ph.D. student at Texas A&M at Galveston, according to NewsFix.com. "Any sort of hard structure that's sunk towards the bottom, you see all sorts of life congregating to these sites."

Similar volcanoes have been discovered off the coast of West Africa and California before, but this was the first time one was found off Galveston's coast, according to Keeney.

"(It's) very unique," Keeney said, "and has not been seen in this part of the Gulf ever before."

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