Believe It Or Not: Oldest Sperm Found!

Pop quiz: how old is the oldest sperm in the world?

If you ask paleobiologist Benjamin Bomfleur, he'll tell you the right answer - 50 million years.

"A 50-million-year-old worm sperm from Antarctica?" he said to The Washington Post in amusement. "Who would have thought that's possible?"

Swedish Museum of Natural History paleobiologist Thomas Mörs, Bomfleur's colleague, found the fossilized cocoon that contained the ancient sperm while on an expedition on Seymour Island in the Antarctic. But it was Bomfleur who noticed "the long, fragile remains of what appeared to be a sperm."

He referred the images of his discovery to Marco Ferraguti, an expert on annelid sperm. Ferraguti used radiometric dating to assess the cocoon and found that the specimen and all within it were "at least 50 million years old." It's the oldest fossilized animal sperm ever found to date.

Considering that "sperm cells are so short-lived and fragile," as Bomfleur told MailOnline, the find is a rare one.

Ferraguti said that the sample found was likely that of a "crayfish worm."

"He added that other, younger examples of fossil sperm have been found preserved in amber in Europe and in cave deposits in Australia," the British publication went on to report.

"This discovery offers an opportunity to discover a great deal about the evolutionary history of micro-organisms for which we previously had little fossil data," Bomfleur explained.

How did the sperm survive for millions of years?

The owner of the sperm made a 2-millimeter cocoon that serves as a protective husk for an egg and sperm during the worm's reproduction phase.

"The cocoon is formed by a sticky mucus that takes several days to harden, but once it does, biological material, such as sperm, can be trapped along its walls," The Washington Post said.

As such, the sperm is preserved within the hardened cocoon.

However, the sperm sample found was fragmented, making it hard for scientists to get more information about the worm that produced the cocoon. On the other hand, remains of other small animals were found in the cocoon.

"Bomfleur explained that though worms themselves don't fossilize well, sperm can be a better clue as to the creator of a given cocoon. This discovery should encourage future researchers to look for similar structures," the news source said.

"There could be a lot of potential hidden gems inside those cocoons," commented University of Bristol's Jakob Vinther, who specializes in invertebrate evolution.

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