Curiosity collected the first samples of material ever drilled from rocks on Mars in the "Glenelg" area. The rover first examined a rock called "John Klein" using its built-in chemical and mineral analysis tools known as Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin). It found carbon, hydrogen, oxygen, phosphorus and sulfur -- which are all key ingredients necessary for life. The sample from John Klein was later compared with a second sample from "Cumberland" that was drilled on May 19, 2013, confirming the initial findings. The first sample also revealed clay minerals and not too much salt, leading scientists to believe that the area could have contained drinkable water at one point.