Pot boiler

[2] In a pre-pottery context, the heating can be done by lining a pit with leather, leaves or clay, and then putting in the water followed by pot boilers directly into the vessel.

Often the broken pot boilers are discarded into middens or domestic waste deposits, which on long-established sites can amount to many tonnes of material.

[2] Reuse as building material is not impossible, but the typical small size of the fragments hinders this use.

Surface "crazing" is not restricted to pot boilers - hearth stones and the surrounds of fireplaces may also show the same structure.

However, since a pot boiler needs to be manipulated into and out of the fire (typically in anthropological observations, using sticks of green wood) at arm's length, they start off weighing up to several kilogrammes, and shrink by fragmentation ; hearth stones and chimney liners are typically larger.

Two incomplete fire-cracked cobbles of unknown date which have been subjected to high heat causing them to crack and break. Date from: Circa 800 BC Date to: Circa AD 1800 (Iron Age to Medieval). Found by fieldwalking on cultivated land near Goole in Yorkshire, England.
Ethnological Museum, Berlin-Dahlem; A Wooden fork and four steatite cooking stones. In most areas of California, native American cooking was done in watertight baskets. First, the acorn meal was mixed with water. By adding red-hot stones, the acorn mush was heated. After cooling, the stones were taken out with a wooden fork and replaced by new ones until the mush or soup was fully cooked.