Lightning photograph courtesy of National Geographic.

If you’ve spent any time on Sanibel Island, especially in the summer, chances are you’ve watched one of those colossal thunderstorms roll in: the sky becomes menacing, the color of a bruise, and BAAAAROOOMM – thunder and lightning are everywhere. This is just about the only thing capable of driving an ocean-loving Sanibel Sea School student indoors.

But what do these beautiful, if inconvenient, thunderstorms have to do with this curious object that can sometimes be found on a Sanibel beach?

Thanks to Tom and Linda Uhler for the donation of this intriguing beach find!

What is it? A worm tube? A piece of dried seaweed? What if we told you that to hold this object is the closest we mere mortals can get to holding a lightning bolt in the palm of our hand?

This is a fulgurite—the result of lightning striking sand. It’s the “pot of gold” at the end of a lightning bolt.

Here at Sanibel Sea School, we mostly concern ourselves with ocean life. However, we are curious and excited about our entire landscape, and sometimes that entails stepping out of our creature-centric box. With that in mind, here are a few words on fulgurites:

Lightning is outrageously hot—hotter than the surface of the sun—and when it strikes, it releases an incredible amount of current and heat to the earth. So what happens when lightning strikes a beach? Moisture and air in the sand are heated so rapidly and to such a degree they create an explosion, pushing molten sand outward and creating a void in the center of the lightning channel. Rapid cooling and re-solidification create the sides of a glassy, root-like tube that traces the path of the lightning as it penetrates the ground.

On the outside, our fulgurite is knobby and gray, made rough by bits of sand clinging to its surface. Inside, however, it is lined with naturally formed silica glass called Lechatelierite—a daunting word for what is actually smooth, gleaming, and simply lovely.

The beauty and power encapsulated in fulgurites make them popular for use in jewelry and other kinds of art. And here, by “other kinds of art”, I mean something totally wild: custom-designed lightning strikes. In 1997, artist Allan McCollum created an installation at the USF contemporary art museum titled “THE EVENT: Petrified Lightning from Camp Blanding”. He fired model rockets with trailing copper wires directly into storm clouds to artificially trigger and direct the path of lightning. To us, this seems downright Herculean. Don’t get too comfortable up there, Zeus!

Florida has more lightning strikes than any other state. So while you’re combing the beach for colorful shells and critters, keep your eyes peeled for something a little less conspicuous — you just might find lightning in the sand.