Paeto, a carbonaceous asteroid, became notable for Element Zero deposits. The deposits, which indicate it was an extrasolar capture, were discovered by the salarians shortly before they found the mass relay in the Pranash [sic] system. Naturally, all element zero was mined out long ago.
The asteroid is named for the clan of Paeto Il Ginon Mal Eneste Dut Solem Ammar, known to humans as Ammar Solem. This shy, retiring eccentric was an undergraduate when more important astrogeologists passed off the first eezo deposits to him. He ran the fateful test that discovered its mass-affecting properties. For three centuries after his death, rival clans fought for credit for the discovery, but the truth won out after a lengthy academic war.