The oldest sperm remains on record date back to the Cretaceous, about a hundred million years ago, and have been discovered inside a female of a tiny crustacean that got trapped in amber in Myanmar.

Furthermore, the crustacean specimen belongs to a hitherto unknown species and has been named as Myanmarcypris hui, which in turn belongs to the class of ostracods, according to a study published Proceedings of Royal Society B.

Among the remains found in amber, the researchers located a female in whose reproductive tract giant sperm cells were found, which makes her the oldest fossil in which sperm cells have been conclusively identified, explains the German Ludwig-Maximilians University, one of the signatories of the study.

Ostracods have existed for 500 million years, and thousands of modern species have been described, thus Finding fossilized shells of these crustaceans is not uncommon.

However, the specimens found now, being preserved in amber, allowed to know details of their internal organs, including reproductive ones.

Thus, they were analyzed with the help of X-ray reconstructions Computer-aided 3D imaging and imaging revealed surprising details of these animals’ anatomy, from their tiny limbs to their reproductive organs.

In one of the females, the researchers they found mature sperm, which was discovered in the receptacles where it was stored after copulation, waiting to be released when the female’s ovules matured.