Considered to be a remarkable finding, scientists have discovered fossilized sperm inside the 50 million-year-old worm cocoon in Antarctica. The researchers have stated that it is oldest animal sperm ever discovered.

Researcher Benjamin Bomfleur from the Swedish Museum of Natural History said that the discovery was not intended and it was just by chance finding. The researchers were on expedition on Seymour Island on the Antarctic Peninsula.

Researcher Thomas Mörs was looking out for small mammal bones and it was then that he came across a fossilized cocoon. After finding the cocoon, Thomas gave it to Bomfleur who identified that it was a clitellate worm cocoon.

When the researchers properly checked the cocoon they found fragments of the creature's sperm. The researchers were stunned to find the same. The clitellate worm's sperm does not last long. This fact made the finding even more special.

The researchers said that the sperm remained preserved because it was trapped in the jelly-like cocoon before it became hard. Radiometric dating was used and it was then found that the sperm dates back to the early Eocene Era. Though the specimen was very well preserved, it did not have any organic material or DNA.

The findings have helped the researchers know that the fossilized sperm is quite similar to modern-day crayfish worms. Thomas said that it is very rare to find fossilized sperms, but Seymour Island is an exception as it the hot spot for fossils. "There could be a lot of potential hidden gems inside those cocoons", said Thomas.