Fossil trackways are simultaneously wonderful and frustrating things. They are preserved bits of prehistoric behavior, but, unless an animal actually dies and becomes preserved in its tracks, identifying exactly what creature left the traces can be fraught with difficulty. (The types of prehistoric environments which preserved tracks often destroyed body fossils, so, when the two are found together, ichnologists celebrate.) Every now and then, though, paleontologists discover a creature which became fossilized with the impressions it left behind. Such is the case with a Cambrian trilobite discovered in the Czech Republic.

The trilobite fossil described by Oldrich Fatka and Michal Szabad is subtle, but significant. At the end of a short burrow is the body of the