Monday on a Devonian shale outcrop near Hamilton, NY, I told the crew this lineage lost vision, then split a plate with my beat-up Estwing and got greeted by a face full of schizochroal lenses from a very smug Phacops cousin — evolutionary history loves a punchline… Anyone else get publicly corrected by a fossil mid-lecture?
Been there — my ‘blind phacopid’ gave me the schizochroal side-eye once I hit it with a 10× hand lens. I now log eye/no-eye by bed and shoot a phone macro to check lens columns later — nice match for this AMNH explainer: https://www.amnh.org/exhibitions/permanent/fossil-halls/what-is-a-trilobite/trilobite-eyes.
Try a quick polarized check before declaring anyone blind: hold your sunglasses over the phone and rotate — the calcite lenses will blink while the matrix stays dull; it’s a 10-second save from smug Phacops payback. Only caveat: recrystallized eyes can fake it, so I also carry a tiny raking LED to catch relief. @nicdavi, have you found cross-pol or the LED works better on weathered shale?
That “face full of schizochroal lenses” after the beat-up Estwing swing is peak Devonian karma. I’ve had good luck misting the split surface and using low raking light — the calcite facets will sparkle while the shale stays dull. If you try @garcia70’s polarized blink, note dolomitization can kill the effect, so I do both — what bed were you on near Hamilton?