The five people trapped inside the Titanic-bound tourist sub could find their bodies turned into “mummies” due to frigid underwater temperatures and the lack of oxygen in the pressurized vessel, experts said.

Nicholas Passalacqua, a director of Forensic Anthropology at Western Carolina University, surmised that if the five passengers died aboard the Titan, their bodies would be oddly preserved inside the submersible.

“Generally in an environment without oxygen, remains will not decompose much because the micro and macro organisms that would work to consume and decompose the tissues will be unable to survive,” Passalacqua told Insider.

Melissa Connors, a director for the Forensic Investigation Research Station at Colorado Mesa University, agreed with the assessment, noting that the cold temperatures of the Atlantic would help dry the bodies if the sub’s heating system were to fail as well.

“So you might end up with mummies,” she told the outlet.

In general, higher temperatures and the presence of bacteria lead to a faster body decomposition rate. And while bacteria typically require oxygen to thrive, anaerobe bacteria that can operate without oxygen can still decompose the bodies of the dead.

There is very little research and precedent on bodies that have been found in highly pressurized, underwater vessels. The decomposition of a normal corpse can take anywhere from weeks to even years depending on the environment.

The morbid outcome stands as one of three major likely possibilities as OceanGate Expeditions’ Titan remains lost less than two hours after submerging into the Atlantic on Sunday morning.

With its oxygen supply forecasted to have run out Thursday morning, the five passengers face dwindling hopes of being rescued alive, although the search and rescue teams have repeatedly said they’re not giving up hope despite the 96-hour window closing.

The US Coast Guard said it was possible Titan resurfaced but lacked the means to communicate its location.

“If it’s on the surface, we’re fairly sure we’re going to be able to find it,” Coast Guard Capt. Jamie Frederick assured reporters Tuesday. 

It’s unclear how long the passengers would be able to survive adrift in the ocean.

Experts have also suggested that the Titan suffered a breach in its hull, which has long been criticized as part of an “experimental design” that diving experts warned would have “catastrophic” impacts on the industry.

A breach would result in the sub likely imploding from the intense pressure of the Atlantic’s depths.