I have been working through the trilobite specimens I dug recently at the Oak Springs Trilobite Site in eastern Nevada.  I came across this feature in the shale that I can't identify.  When I split the piece of shale I found this oval-shaped feature on both halves. It could be geologic or possibly some sort of fossil.  It has the same reddish color as some of the trilobites I found, but it's clearly not a trilobite.   When I turned one slab over I found the shape extended through the thickness o