Why Are Shark Teeth Black?

Dark shark teeth can get their color from changes during burial. The color reflects the conditions around a tooth, not a dependable clock showing how old it is.

The Florida Museum's fossil-shark-teeth guide explains that mineral-bearing water enters pore spaces in buried teeth. This process, permineralization, helps preserve them. Different minerals and their reactions can produce different colors; oxidized iron, for example, can give fossils reddish-brown tones.

Not every fossil tooth is black

The museum documents fossil-tooth colors including blue-gray, black, orange-red, white and green. Modern teeth are typically white, but pale areas can persist in fossils too. A white crown therefore does not establish that a tooth was recently shed.

Treat color as one clue alongside the tooth's anatomy and where it was found. It cannot independently establish an identification or a precise age. A dark triangular pebble remains a pebble; shape and color alone do not make it a tooth.

Why this matters when identifying a find

Before asking how old a tooth is, establish whether it is a tooth at all. Photograph both sides and the edge beside a scale. Compare the crown, root and any surviving serrations with the Florida shark-tooth identification guide.

Keep the observation and interpretation separate in your notes. For example: “dark fragment, root uncertain, found in the shell line.” That is more useful than recording an assumed species and age from its color. If the distinguishing parts are missing, leave the identification open.

Do not bleach or polish a find to make it resemble a reference photograph. Use the fossil-tooth cleaning guide before choosing a cleaning method, particularly for a fragile specimen.

Can color date a shark tooth?

For age estimates, the Florida Museum points to the geological age of the sediments containing the fossil. That is different from saying a black tooth is a certain number of years old. The beach where a loose tooth was picked up may not reveal its original burial layer.

Record the beach, date and circumstances of the find. A specialist may be able to narrow down an identification or geological context, but an honest answer can remain broad. A photo-identification suggestion should not be treated as a laboratory age estimate.

For the related question about dark seashells, see why some shells are black. Keep the two questions separate rather than applying one color explanation to every beach find.