Transparent outer surface is actually striated with fine lamina, as demonstrated below on high-magnification images from the anterior edge of  the tip, middle and base of the cusp.  The lamina appear to maintain continuity along the length of the cusp, but outer layers are thinner at the base.  Inner lamina merge with white matter at the tip -- which appears black in the high-power micrographs that use transmitted light.   Wear surfaces buried inside the laminar layers suggest that the tooth actually grew continuously by adding new layers of enamel to the outer surface  --  periodically recoating the worn element with a new and thicker layer, and simultaneously sharpening and repairing itself.  Click on image to enlarge.

• Estimated Age: about 450 million years old.
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• Comments: Scale Bar on pictures 1-2 is 0.5 mm, on lower pictures scale bar is  0.01 mm (10 microns).  About 50 times more conodonts were recovered from this soft amorphous vein than were found in the hard crystalized limestone surrounding it.  This was the largest of about 250 elements recovered in this sample.  Pictures 01 - 03  were taken under oil immersion.   Notice the "white matter" is coated by a tough layer that is almost transparent.  This layer coats even the smallest denticles, and often tapers to a sharp point.  The element behind these "crossed swords" may have been broken by 450 million years of sediment pressure, and gradually fused again into one piece.