The Serapeum was the tomb of sacred bulls, associated with the cult of the god Apis. The bulls were chosen from the herd and sacrificed, thereby being deified. The mummification ceremony lasted 70 days, after which time the mummies of the bulls were placed in underground tombs. The sarcophagi of 24 Apis bulls were found by archaeologist Auguste Mariette in 1850, in the deep galleries of the Serapeum at Saqqara.