Of all the props Mark Calzaretta has used to help juries understand environmental contamination, his favorite was Jell-O in a fish tank.

As founding partner and director of litigation consulting at Magna Legal Services, a Philadelphia-based company that provides legal support and jury consulting, Calzaretta works with attorneys to do jury research, develop case strategies, prepare witnesses, and create visual aids to help tell the stories behind a case in easy-to-understand terms.

“We create the visual strategy to go along with the story,” he said.

Calzaretta, who has a degree in psychology and anthropology, has worked in litigation consulting for more than 15 years. He wouldn’t discuss his clients, though his website says he’s worked on “numerous asbestos cases” and “numerous toxic tort cases.”

Complex environmental cases often need visuals to explain to juries how contaminants from one place move to another. Magna sometimes flies planes over a site and uses lasers to map out terrain, or drills into bedrock below contaminated sites to get samples of what lies underneath.

The Jell-O was used to help explain the term “DNAPL.” Short for “dense nonaqueous-phase liquids,” environmental engineers use the acronym to describe toxic contaminants that are both denser than water and don’t dissolve.

Chlorinated solvents such as tetrachloroethene and trichloroethene are examples of DNAPLs that linger in the soil and water around old manufacturing sites.

A company tried to convince the jury it was impossible that residual chemicals from its product could have fallen to the bottom of a pond and seeped into groundwater. Calzaretta’s team brought in a five-gallon fish tank into the court room, dumped a dessert cup of green Jell-O in the tank, and let the jury watch it sink to the rocks on the bottom.

If they waited long enough, the team explained, the Jell-O would ooze down into the rocks to layer underneath.

“That’s what happens when you put contaminants into the water system,” Calzaretta said. “And all the jurors were like, ‘That’s awesome. I totally get it! How could it not get in the groundwater?’”

This piece originally appeared in Bloomberg Environment on March 18, 2019.