Scientists searching for what they thought to be a shipwreck found something entirely unexpected in the Gulf of Mexico instead.

“It looked like a shipwreck,” Thomas Heathman, a Texas A&M-Galveston marine biology student, told KHOU-TV of the image that was first seen on an acoustic survey. “And then once we get down there, we see this structure that we’ve never seen before. Never seen anything like it in the northern Gulf of Mexico.”

A robotic vehicle tethered to the Okeanos Explorer, a vessel owned by the National and Atmospheric Administration, was on its 12th dive last week as part of the expedition in the Gulf. At a depth of more than 1,900 meters, the robot picked up images of bacterial mats, bamboo corals, shrimp and other sea life.  

Approaching the area of the suspected shipwreck though, the researchers saw not a man-made object but a natural phenomenon, according to NOAA’s dive report.

Image source: NOAA video

Image source: NOAA video

Image source: NOAA video

Image source: NOAA video

It was a “flower-like extrusion” created by an asphalt volcano. Nicknamed the “tar lily,” NOAA said it is the first of its kind spotted in the Gulf.

“Once we got up to it, we were thinking, ‘This is not a ship.’ It was an ‘oh my gosh’ moment,” Heatherton told the Houston Chronicle.

NOAA described each “petal” as being a tar extrusion that was curved and layered as a result of asphalt rising and from the sea floor and coming into contact with the water.

A "petal" of a tar lily. (Image source: NOAA Okeanos Explorer Program)

A “petal” of a tar lily. (Image source: NOAA Okeanos Explorer Program)

Life was abundant on both of the tar lilies the team found, and no bubbles indicating gas or oil were observe coming from the structures. They were estimated to be hundreds if not thousands of years old.

Image source: NOAA video

Image source: NOAA video

Image source: NOAA video

Image source: NOAA video

Image source: NOAA video

Image source: NOAA video

While the discovery of the tar lilies was exciting, the team was hoping they had found the fourth shipwreck after investigations have already been conducted on three related sunken ships in what’s called the Monterrey Wreck area. According to KHOU, the thought is that a pirate ship in the early 19th century told by a government to attack the ships from other countries. Previous expeditions of the wrecks have brought back artifacts and more are planned for the future.

All in all, Texas A&M biology professor Gilbert Rowe told the Chronicle that this latest discovery highlights yet again how “we know more about the moon than we know about the deep oceans.”

See more of the tar lilies in NOAA’s dive video on its website.