The sample ALH84001 contains a distinctive oxygen isotopic composition which points to an origin from Mars. These measurements were taken from the Viking Missions in the 1970's.
The "POTATO" rock, which has been the topic of conversation for the media as well as the scientific community is said to have formed beneath the surface of Mars 4.5 billion years ago. This was when Mars was wetter, warmer and more closely relatable to a tundra-like landscape.
The other 11 samples are igneous meteorites which range in age starting from 1.3 billion years old. This is much younger than typical meteorites which are generally of the order of 3.5 billion years old.
These meteorites contain gas bubbles which have a higher concentration of volatiles than regular meteorites. These measurements correspond with the measurements taken by the Viking missions, as seen above.