The kings of the Twelfth Dynasty were buried in pyramid complexes based on those of the Fifth and Sixth Dynasties.[76] In the Old Kingdom, these were made of stone bricks, but the Middle Kingdom kings chose to have theirs made of mud bricks and finished with a casing of Tura limestone.[77] Private tombs, such as those found in Thebes, usually consisted of a long passage cut into rock, with a small chamber at the end. These tended to have little or no decoration.[78] Stone box sarcophagi with both flat and vaulted lids were manufactured in the Middle Kingdom, as a continuation of the Old Kingdom tradition. The motifs on these were more varied and of higher artistic quality than that of any sarcophagi produced before and after the Middle Kingdom.[79] Additionally, funerary stelae developed in regard to images and iconography.