However, early masonry ovens going all the way back to ancient Egypt were typically made of native clay, often tempered (to minimize cracking) with gravel, sand, and/or straw. Smaller ovens were built over forms made of sand, or a rough, basket-like shell made of sticks. After the form was covered, the sand was shoveled out, or the sticks burnt. Clome ovens were a modular (and sometimes portable) variant—essentially a large, upside-down clay pot with an door opening cut into the side. They were often surrounded with brick as they were built into English chimneys, allowing coals and ashes to be swept onto the common hearth, and smoke to go into the chimney. "Like the Athenian cooking bell and the primitive quern, the rough clay oven had its counterparts for several thousand years, among its descendants being our own seventeenth-century Devon gravel-tempered clay wall ovens... Built into the side wall of the open hearth so that from the front only the opening was visible, these primitive-looking ovens were still being produced in Barnstaple potteries as late as 1890".