Concrete used by the Romans to build their cliff-side cities, bridges and sea walls more than two thousand years ago have withstood time and still stand strong today, while modern concrete exposed to seawater deteriorates within decades.

Now researchers may have figured out what has made Roman concrete so durable, and the University of Utah's Marie Jackson thinks she might be able to recreate it, per the Washington Post. The Roman's secret: the concrete contains tiny crystals that keep it from fracturing.

Why it matters: If successful, the concrete could be used to make sea walls that can protect shoreline environments from flooding and rising seas.

The findings, as detailed by WaPo:

• Jackson and her colleagues learned that Roman concrete behaves "in many ways, like volcanic deposits in submarine environments." It is filled with tiny growing crystals that act "like tiny armor plates" and keep the concrete from fracturing.
• A series of tests run by Jackson's team revealed that the aluminous tobermorite crystals were created from a chemical reaction: when seawater flooded through the cracks in the concrete, it reacted with a mineral known as phillipsite found naturally in the volcanic rock.

What's next: "The Romans mined a specific type of volcanic ash from a quarry in Italy" writes WaPo. "Jackson is attempting to recreate this durable concrete using San Francisco seawater and more abundant volcanic rocks. She has several samples sitting in ovens and jars in her lab, which she will test for evidence of similar chemical reactions."