Scientists consider that a 20-centimeter siltstone phallus from the Upper Palaeolithic period 30,000 years in the past, present in Hohle Fels Cave close to Ulm, Germany, may have been used as a dildo. Artifacts from the Upper Paleolithic of a kind referred to as bâton de commandement have been speculated to have been used for sexual purposes. They typically have gentle bumps supposed to provide additional stimulation. A penis sleeve is a cylindrical machine that is positioned on the shaft of the penis, with the goal of accelerating stimulation for the particular person being penetrated. Urethral sounds are rods, known after the nautical "sounding rods" that measure water depth, - usually silicone or metallic, often with a ball at one finish - inserted into the urethra sex dolls for women sexual stimulation. Dildoes are talked about a number of occasions in Aristophanes' comedy of 411 BCE, Lysistrata.