Strabo Geography 17.1.34

[34] One extraordinary thing which I saw at the pyramids must not be omitted. Heaps of stones from the quarries lie in front of the pyramids. Among these are found pieces which in shape and size resemble lentils. ¹ Some contain substances like grains half peeled. These, it is said, are the remnants of the workmen’s food converted into stone; which is not probable. ² For at home in our country (Amasia), there is a long hill in a plain, which abounds with pebbles of a porus stone, ³ resembling lentils. The pebbles of the sea-shore and of rivers suggest somewhat of the same difficulty [respecting their origin]; some explanation may indeed be found in the motion [to which these are subject] in flowing waters, but the investigation of the above fact presents more difficulty. I have said elsewhere, ⁴ that in sight of the pyramids, on the other side in Arabia, and near the stone quarries from which they are built, is a very rocky mountain, called the Trojan mountain; beneath it there are caves, and near the caves and the river a village called Troy, an ancient settlement of the captive Trojans who had accompanied Menelaus and settled there. ⁵