The deuterium/hydrogen ratios are consistent with cometary origin

If there ever is a meteorite type likely to preserve extra-terrestrial life, it is the CI1 chondrites described in the article. They are micro-breccias thought to be regolith (in this case, material weathered by water) from the surface of the parent body – probably an asteroid or comet. These extremely rare meteorites crumble to dust when they get wet because their microscopic particles are held together with clay and water-soluble minerals. Only 5 falls have been directly observed, Orgueil in 1864 being the biggest (4 others were found in Antarctica). The CI1s are soft enough to be cut with a knife, and early observers described them as humus- or bitumen-like. They are highly carbonaceous and contain complex organic compounds such as kerogen, long-chain fatty acids, protein amino acids, and the breakdown products of chlorophyll. The microscopic filaments exposed on fresh surfaces look very much like bacteria and certainly are not biological contaminants because they lack nitrogen, as do multi-million year old fossils from Earth.