Advertised by signs all along the freeway, one of the country’s odder roadside attractions stands atop 5,013-foot Texas Summit, along I-10 at exit 322: The Thing (520/586-2581, $2). A gas station, a gift shop, and a Dairy Queen stand in front of a prefab shed full of stuff ranging from a Rolls Royce said to have been used by Adolf Hitler to The Thing itself, a mummified corpse whose “secret identity” has yet to be revealed. “What is it?” the signs ask.