In a rare find, scientists have examined guts, legs, and gills from an animal that was preserved for nearly 500 million years. The ancient soft parts are offering new insights into the behavior of trilobites, the insect-like creatures that ruled Earth’s early seas for hundreds of millions of years.

Paleontologists have identified more than 20,000 species of trilobite, but little is known about exactly how the animals moved around or what and how they ate. That’s because the soft tissues of the undercarriage are usually long gone by the time the harder exoskeletons mineralize into the distinctive alien-looking fossils.

Now, Diego García-Bellido and Juan Carlos Gutiérrez-Marco have gotten a good look at three specimens of a 478-million-year-old trilobite