The meteorite was found on a windswept gravel plain about 40 kilometers south of the village of Bordj Badji Mokhtar, in southwestern Algeria, by a Tuareg prospector named Ahmed Ag Mohammed.

It was, in his words, "darker than the other stones and heavier than it looked." He photographed it next to his water bottle for scale and walked it back to camp.

The 2.4-kilogram stone passed through three intermediaries before reaching the laboratory of cosmochemist Yuki Tanaka at the Tokyo Institute of Technology in late February.

Tanaka ran the standard isotopic analyses on a 12-gram subsample. The aluminum-26 to magnesium-26 ratios returned a formation age of 4.612 billion years, with an uncertainty of plus or minus seven million.

The solar system is, by every current model, 4.567 billion years old. The meteorite, designated NWA 16842 and informally nicknamed Erg Chech Elder, predates it by approximately 45 million years.

What is unusual about NWA 16842 is the bulk-rock age. The entire meteorite, not just embedded grains, dates to before the sun.

This is not, by itself, impossible. Meteorites containing presolar grains, tiny inclusions that condensed in the atmospheres of older stars, have been known since the 1980s. Some of those grains are billions of years older than the solar system.

What is unusual about NWA 16842 is the bulk-rock age. The entire meteorite, not just embedded grains, dates to before the sun.

Tanaka's interpretation is that the parent body of NWA 16842 formed in a dense molecular cloud, possibly the same one that later collapsed to form the solar system, and survived more or less intact through the collapse and the protoplanetary disk phase.

If correct, the meteorite represents a kind of fossil of the pre-solar nebula, a piece of rock that watched the sun ignite.

The mineralogy supports the interpretation. The meteorite is dominated by an unusual aluminum-rich silicate assemblage that resembles theoretical models of high-temperature condensates from massive-star outflows.

Trace concentrations of silicon carbide and graphite, isotopically distinct from solar values, suggest contributions from at least three separate stellar sources.

The discovery has prompted a small surge of interest in the Erg Chech strewn field, where several other unusual meteorites have been collected in recent years.

Algerian authorities and the African Meteorite Society have moved to formalize collection protocols, partly to protect scientific value and partly to ensure that local finders receive fair compensation.

Ag Mohammed, who has continued to prospect, has agreed to a percentage of the academic sale price and has been credited as the discoverer in the forthcoming Geochimica et Cosmochimica Acta paper.

Tanaka plans to return the main mass of the meteorite to Algiers for permanent curation at the Centre de Recherche en Astronomie, Astrophysique et Géophysique once analytical work is complete.

It is a strange thing to hold in a gloved hand a piece of rock older than the star that lights the room.

The light from the desk lamp, Tanaka has noted, is younger than the stone it illuminates by approximately 45 million years.