An Area Of Interest In A Shark Tooth Thin Section

[The QCC]

The shark's tooth is the second in a series of thin sections I am making of fossils.
The tooth is relatively small at 10mm x 9mm and the final thin section is not all that promising as a large print subject. After looking at the tooth through a magnifying glass I noticed what looked like serrations on one edge. Looking at the thin section through a microscope confirmed there is something akin to serrations.
This presentation concentrates on that area of the thin section.

Click on the photo to see the thin section photos.

I have elected to use my web server instead of the forum because there are 8 photos.

Photo 1 is the tooth before it was ground down to a thickness of 70microns with the area of interest marked.
Photo 2 is a closer look at the serrated edge.
Photos 3 to 8 are through the a polarizing microscope.
Photo 3 is a 5x magnification of the area.
Photo 4 shows the texture of the tooth above the serrations.
Photo 5 is the same area with the full wave lambda plate inserted.
Photo 6 is a magnified 10x.
Photo 7 is 10x magnification of a seashell fragment. I added it because the texture of the seashell is quite similar to the shark tooth.
Photo 8 is the textured area at 50x magnification.

I have to admit I do not know a lot about shark teeth, but the selected area looks like serrations and the texture of the shark tooth is remarkably similar to a seashell.
Can I assume shark teeth and seashells have similar composition?