It's one of the biggest mysteries in modern aviation history. In March 2014, Malaysia Airlines flight MH370 took off from Kuala Lumpur International Airport en route to Beijing and lost communication about 38 minutes into the flight. Military radar tracked the aircraft as it veered off course before the signal (and the plane) disappeared somewhere over the Andaman Sea and Indian Ocean.

All 12 crew members and 227 passengers were presumed dead, and search-and-rescue efforts yielded no signs of the doomed plane apart from a few pieces of debris that washed up on coastal shores months later. Now, scientists have partially reconstructed the possible origin and drift path of that debris via a novel means: extracting data about ocean temperatures stored in shells of barnacles, according to a new paper published in the journal AGU Advances.

“Knowing the tragic story behind the mystery motivated everyone involved in this project to get the data and have this work published,” said co-author Nasser Al-Qattan, who recently received his PhD from the University of South Florida. “The plane disappeared more than nine years ago, and we all worked aiming to introduce a new approach to help resume the search, suspended in January 2017, which might help bring some closure to the families of those on the missing plane.”

The inspiration for a fresh search strategy struck Gregory Herbert, an evolutionary and conservation biologist at the University of South Florida, a few years ago after seeing photographs of a piece of debris from the downed plane—a flaperon (a control surface designed to control the roll or back of an aircraft and reduce stall speed) found on the beach of an island called Saint-Andre, Reunion, in late July 2015. Serial numbers confirmed it had come from MH370. The flaperon was covered in barnacles that had likely colonized it shortly after the plane went down.

Herbert's expertise is the study of shelled marine invertebrates such as oysters, conches, and, yes, barnacles, and he has spent two decades developing a method to measure ocean temperatures as recorded in those shells. In 2010, for instance, he co-authored a study of 400-year-old oyster shells that revealed the first permanent English settlement in America, Jamestown, had been plagued by drought. The search efforts for MH370 focused on a stretch of several thousand miles along a corridor running north to south, dubbed the "Seventh Arch." It was believed the plane would have glided along that arc after running out of fuel. Because ocean temperatures change so rapidly along the arc, Herbert thought he might be able to more precisely pinpoint where MH370 ultimately landed with his new method.

Ocean circulation models have previously been used to reconstruct the origins of floating objects such as plastic pollution, human remains, sea turtles, and so forth, but these models become increasingly inaccurate as the distance and duration of the drift increases. But barnacles frequently form colonies on floating debris, and the ratio of oxygen isotopes in their shell layers is temperature dependent: the warmer the waters at the time a layer formed, the lower the ratio. So, one can determine the history of sea surface temperatures by measuring those isotope levels in the shell layers, much like tree rings record the climate history along with a given tree's age.

This, in turn, can help constrain where a floating piece of debris, like the flaperon, could and could not have been. However, "Simultaneously solving where and when a drifting object experienced each sea surface temperature is the critical challenge in stitching together [sea surface temperatures] recorded from barnacle shells into a unique drift track leading back to a specific drift origin," the authors wrote.

A French biologist named Joseph Poupin was one of the first to examine the flaperon when it was discovered, covered with dead barnacles that were firmly attached with tissue still inside (and smelly, to boot). Poupin estimated the largest of those barnacles were between 15 and 16 months old—"possibly old enough to have colonized on the wreckage very shortly after the crash and very close to the actual crash location where the plane is now,” said Herbert. “If so, the temperatures recorded in those shells could help investigators narrow their search.”