It's a basic trilobite for use as a medallion or decoration, built in Autodesk 123D Design from geometric solids. Design inspired by Girl Genius webcomic's Heterodyne family crest.
They use several designs for the Trilobyte crest, including something similar to this. There is also one without the "head" oval, one with eyes, one with a Fleur-de-lis on the head (thorax?). I might work those in for variety. Also, I'm working on one with deeper relief, as this one seems a bit shallow. We'll see once I have painted it.