Inner Space Cavern was discovered in May 1963 on land of W.W. Laubach by a core-drilling team of the Texas Highway Department. Exploration began in November 1963 and continues to present. Carved by water from Edwards Limestone, the cave lies along the Balcones fault and is estimated to be 100 million years old. Ninety-five percent of its formations are still growing. The cave was apparently open during the late Pleistocene, 20,000 to 45,000 years ago, because bones of many extinct mammals have been found in debris cones filling former natural entrances. The remains include sabre-toothed cats and mammoths.