From trilobites to tyrannosaurs, most fossils are of creatures with hard shells or bones. These materials don’t easily biodegrade and sediment has time to build up around them and turn them into a record of the creature that is still with us millions of years after it has died. Soft-bodied organisms like worms, on the other hand, decay rapidly and their fossil record is decidedly patchy.
In exceptional circumstances, however, their remains are preserved and sometimes in the most unusual places. With the right detective skills, palaeontologists can use such discoveries to open up whole new windows on the history of life on Earth. A recent discovery found in 50-million-year-old rocks from Antarctica has yielded a particularly incredible example: fossilised worm sperm.