The results showed that the sperm belonged to a species of annelid worms. Thomas Mörs of the museum was searching for mammal remains when he stumbled upon the fossil of a cocoon. Leeches, earthworms, and some other similar animals create cocoons which can contain sperm and eggs released into the surroundings. Ferraguti used radiometric dating to assess the cocoon and found that the specimen and all within it were “at least 50 million years old”.

50-million-year-old sperm sample was found in a worm cocoon in Antartica.

According to the study, It is still not clear what these creatures look exactly and where in the taxonomy they should belong to, but the sperm closely resembles those of the crayfish worms, which are leech-like and live on freshwater lobsters, Newsweek has learned. He passed the artifact onto a colleague named Benjamin Bomfleur, who recognized sperm hidden within the rocky matrix. “Who would have thought that’s possible?” In the case of the fossilized cocoon, the worm sperm possibly got entangled in the wall material before the cocoon fossilized.

Scientists may have disclosed the answer to one of the most intriguing questions, even though very few scientists would actually admit they have indeed had this curiosity, namely, to date the oldest traces of sperm.

There will be no extractable DNA left in the sperm fragments, Bomfleur adds, because the chemical make-up of the organic material would have changed from its original composition over such a long time.

Dr. Bomfleur told the BBC that this was a “remarkable discovery” because “sperms are very transient, very short-lived, with soft cellular structures”.

The downside, Bomfleur said, is that the sperm was not completely intact. They were most probably a product of the crayfish worm. According to Nature magazine, the oldest animal sperm previously discovered came from springtails trapped in amber, and was thought to be 40 million years old.

After being published in scientific journal Biology Letters on Wednesday, news of the find went global on Thursday, with Bomfleur telling The Local that worldwide press requests had been “coming in like an avalanche”.

More importantly, Bomfleur explained that though worms themselves don’t fossilize well, sperm can be a better clue as to the creator of a given cocoon. And this example should encourage the discovery of similar structures by researchers.

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

The sperm sample was accidentally discovered by scientists as they were effecting other researches in the Antarctic region.