sentences:  Some individuals outside of the United States have lived in excess of 70 years in captivity.During her tenure at the zoo, Mona inhabited a pen with access to two concrete-floored stalls in the zoo's pachyderm building.The effect of concrete floors on captive elephants has been shown to be detrimental, and Mona's feet were badly damaged by the so-called "Zoo-Genic Elephant Foot Disease".