The answer to the question: What was much of the mortuary temple built from that left it susceptible to erosion? is inside the article: The mortuary temple is located at the base of the pyramid's Eastern face. It is larger than is typical for the period. Archaeological evidence suggests that it was unfinished at Neferirkare's death, and was completed by Neferefre and Nyuserre. For example, while the inner temple and statue niches were built from stone, much of the rest of the temple, including the court and entrance hall, was apparently hastily completed using cheap mudbrick and wood. This left large portions of the mortuary temple susceptible to erosion from rain and wind, where stone would have given it significant durability. The site was less aesthetically impressive, although its basic layout and features remained roughly analogous to Sahure's temple. Its enlarged size can be attributed to a design decision to build the complex without a valley temple or a causeway. Instead, the causeway and temple, whose foundations had been constructed, were diverted to Nyuserre's complex.The temple was entered through the columned portico, and columned entrance hall which terminates into a large columned courtyard. The columns of the hall and courtyard are made from wood arranged into the form of lotus stalks and buds. The courtyard is adorned with thirty-seven such columns; these columns are asymmetrically positioned. The archaeologist Herbert Ricke hypothesized that columns near the altar may have been damaged by fire and removed. A papyrus fragment from the temple archives corroborates this story. A low stepped ramp in the courtyard's west leads to a transverse (north-south) corridor which leads south into storerooms and north into another smaller corridor containing six wooden columns through which the open courtyard of the main pyramid can be accessed. It is in the southern storerooms that the Abusir papyri were discovered by graverobbers in the 1890s. Beyond the storerooms is a gate which has another access point to the main pyramid's courtyard, and through which a second excavated south-western gate leads to Khentkaus II's complex. Finally,..., can you guess it ?
The answer to this question is:
mudbrick and wood