size and therefore minimum air resistance. In addition, leaden sling-bullets are small and difficult to see in flight; their concentrated impact is also a better armour-piercer and better able to penetrate a body. In some cases, the lead would be cast in a simple open mould made by pushing a finger or thumb into sand and pouring molten metal into the hole. However, sling-bullets were more frequently cast in two-part moulds. Such sling-bullets come in a number of shapes including an ellipsoidal form closely resembling an acorn; this could be the origin of the Latin word for a leaden sling-bullet: glandes plumbeae (literally 'leaden acorns') or simply glandes (meaning 'acorns', singular glans). Other shapes include spherical and (by far the most common) biconical, which resembles the shape of the shell of an almond nut or a flattened American football. The ancients do not seem to have taken advantage of the manufacturing process to produce consistent results; leaden sling-bullets vary significantly. The reason why the almond shape was favoured is not clear: it is possible that there is some aerodynamic advantage, but it seems equally likely that there is some more prosaic reason, such as the shape being easy to extract from a mould, or the fact that it will rest in a sling cradle with little danger of rolling out. It is possible as well that the almond, non-circular shape, made the bullet spin in flight in a helicopter or disc like effect adding to the flight distance. Almond-shaped leaden sling-bullets were typically about long and about wide, massing approximately . Very often, symbols or writings were moulded into lead sling-bullets. Many examples have been found including a collection of about 80 sling-bullets from the siege of Perusia in Etruria from 41 BC, to be found in the museum of modern Perugia. Examples of symbols include a stylized lightning bolt, a snake, and a scorpion – reminders of how a sling might strike without warning. Writing might include the name of the owning military unit or commander or might be more imaginative: "Take this", "Ouch", "get pregnant with this" and even "For Pompey's backside" added insult to injury, whereas dexai ('take this' or 'catch!') is merely sarcastic. In Yavne, a sling bullet with the Greek inscription "Victory of Heracles and Hauronas" was discovered, the two gods were the patrons of the city during the Hellenistic period. Julius Caesar writes in