The Natural Science Center of Greensboro’s newest traveling exhibit, “Accidental Mummies of Guanajuato,” showcases 30 Mexican mummies on loan from the Museo de las Momias de Guanajuato.

And yes, they are accidental mummies.

Unlike bodies mummified through an embalming and wrapping process, accidental mummies form only in certain climates and conditions.

These are among 112 discovered in a cemetery in Guanajuato, Mexico. This is the first time they have been exhibited on the East Coast.

In 1865, Guanajuato implemented a graveyard tax because cemeteries were becoming overcrowded. The grave tax was nominal and one that families could pay over the course of three years. If unpaid, coffins were uprooted and the gravesites were used again. The mummies were discovered when the graves were uncovered.

They came from the middle sections of the wall tombs and were encased in wooden coffins and airtight cement, so only part of the decay process occurred. The rest of the bodies and clothing, which normally would have deteriorated, survived.

Natural mummification occurs throughout the world – almost always in areas with extreme climates, where dry sand or freezing cold stops the natural decaying process.

The underpaid caretakers began to charge admission to view the bodies. The first El Museo de las Momias – mummy museum – opened in 1894. The grave tax was eliminated in 1958.

Bones often survive the decay process and provide the main body of evidence for determining age, gender, race and possible cause of death. Scientists also examine teeth to determine diet, age and health.

The dead include a physician, a witch, miners, infants and murder victims.

The phenomenon included rich, poor, young and old. Some of the mummies are more than a century old; others are relatively modern.

Some articles of clothing are still intact on many of the remains. All of them have skin in varying degrees of disintegration. And all were discovered with open mouths, the result of decaying jawbones.

The exhibit ends Dec. 30.

At the exhibit, you can learn more about the science of mummification in a forensic lab. The skeletal structures, internal organs and cellular composition of mummies can be viewed through diagnostic tools such as endoscopy, X-ray, molecular analysis and forensic reconstruction.

The Natural Science Center of Greensboro is at 4301 Lawndale Drive, Greensboro. Hours: 9 a.m.-5 p.m. daily. Admission (with the mummy exhibit): $18; $17 for ages 3-13 and 65 and older; 2 and younger, free. Details: 336-288-3769; www.natsci.org.