Strange Glass Spheres Found in Ancient Florida Clams Point to Meteor Strike

This initially appeared in the July/August issue of Discover journal as “Concept in a Clam.” Guidance our science journalism by becoming a subscriber.


In wealthy fossil deposits in southern Florida acknowledged as the Pinecrest beds, historic clams sit nestled in a mix of sand and clay, waiting to convey to their tales. In 2006, Michael Meyer joined his fellow undergraduates as they searched a quarry there for the fist-sized time capsules of historic environments. The pupils ended up seeking inside the clams for benthic foraminifera, single-celled organisms whose shells consider on diverse styles depending on their environments. Coiled or straight, spiraled left or ideal, the foraminifera can expose what was going on in their entire world 3 million years ago, when the beds ended up deposited. But Meyer, now an assistant professor of Earth systems science at Harrisburg College of Science and Know-how in Pennsylvania, located a little something else in the clams, much too — nevertheless it took him in excess of a ten years to learn the importance of his industry excursion obtain.

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(Image: Michael B. Meyer)

In His Personal Words and phrases:

“We ended up opening these lifeless clams and instantly transpired on all of these minimal spheres. I thought, “What the heck are these?” They ended up the exact measurement assortment as benthic foraminifera, but no a person knew what they ended up.

I collected all 84 of them and went back again to lab to process them. I also despatched out a lot of e-mails, but folks explained they did not assume they ended up anything at all. Others suggested a few of high-priced analyses on exceptional tools that an undergraduate just cannot access. We ended up equipped to test the spheres by X-ray spectroscopy all over two weeks after original discovery, but that only told us the spheres ended up “silica wealthy,” and that was it.

I kept them on a slide in a box, and for the past 13 years, when I had some time, I would deliver out the spheres. My colleagues who know me very well would say, “How are all those minimal bizarre spheres accomplishing?” As I matured as a researcher, I would speak my way on to lab tools when I could get some free of charge analyses completed. 

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Michael Meyer pictured. (Credit history: Michael Meyer)

Ultimately, in 2018, a additional sensitive X-ray spectroscopic evaluation uncovered that the spheres are microtektites: very small bits of glass that kind when a meteorite slams into Earth and spews molten content in a wonderful mist.

But there are nevertheless a several mysteries: These microtektites are large in sodium, which is unconventional since microtektites are created of silica and never commonly include sodium. We nevertheless just cannot totally describe that. We also never know when they ended up fashioned.

The quarry exactly where we located the clams has considering the fact that been stuffed as portion of a genuine estate enhancement, so there is no way to go back again and dig for additional. We’ve been asking area fossil hunters to search in other quarries and get this certain sort of clam and sediment samples to see if we can pull out any additional microtektites that may well fix these mysteries.”

— As told to Jeanne Erdmann