Mystery fossil #64 is...

the fossil kelp Paleocystophora subopposita

Paleocystophora subopposita is a brown alga, just like the giant kelp found off of California's Monterey Peninsula. Although the color of brown algae can range from pale beige to nearly black, their brown color is due to a particular pigment called fucoxanthin. All living brown algae are multicellular, primarily marine, and range in size from tiny filaments to huge strands many meters in length. There are about 1,500 to 2,000 species of brown seaweeds known today.

This specimen of Paleocystophora subopposita is from the Miocene Monterey Formation of southern California. Read more about brown algae in the fossil record. We've featured a kelp Mystery Fossil once before — see Mystery Fossil #4.

Read more about algae in general and what characteristics are used to distinguish between the different groups on the Tree of Life website. A slide show of various brown algae can be seen at the Smithsonian Institution's website.
 

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