Not long ago I received an unprepared asaphid trilobite, Asaphus lepidurus, with the intention of honing my still very green, nascent preparation skills.
From my initial impression, I doubted that the left cephalon was complete, but was instead busted. Turned out it was all there!
The reason it was being offered for sale at a significantly reduced price was because of some issues that would not make it a museum quality specimen, such as shell discolouration and some minor chipping. This was how it looked in its initial state: