rare event. Hexaplex may have cycles of other lengths which inspired this statement: a seven-month cycle for harvesting Hexaplex was claimed by Pliny and confirmed by modern researchers, while Hexaplex appears to have a yearly behavioral cycle in which it burrows in the sand in summer and emerges to swim in winter. Other sources claim that the 70-year cycle was a miraculous occurrence which no longer occurs, or else that the decrease in Hexaplex population numbers may have caused this behavior to cease. There are two other snails that produce the same dye as Hexaplex trunculus: Bolinus brandaris and Stramonita haemastoma, so how do we know which one is the Ḥillazon? Some argue that dye from any of these species would be valid. Alternatively: Hexaplex trunculus contains more natural indigo and thus is a more natural source for blue tekhelet, and archaeological finds show Hexaplex trunculus being processed separately from snails of the other species, suggesting that a different color was derived from this species. Trapping the Ḥillazon is a violation of Shabbat. However, according to some rishonim, in general it is permitted to capture slow-moving animals like snails on Shabbat (as capturing them requires only a trivial effort - בחד שחיא). This contradiction suggests that the hillazon is not a snail. Hexaplex supporters argue that since Hexaplex tends to camouflage itself and hide in the sand, capturing it is a difficult process and thus (by some opinions) forbidden. Rambam, describing the Ḥillazon, says that "its blood is as black as ink", which is not true of Hexaplex. Hexaplex supporters argue that this statement has no apparent source earlier than Rambam, and appears to be based on a mistaken statement by Aristotle. In any case, a black precipitate can in fact be derived from Hexaplex, which is then refined into dye. Tractate Menachot and the Rambam explain the process for making the dye for tekhelet, and neither of them mention explicitly that it needs to be placed in the sunlight. Putting the dye in sunlight is a requirement to make the dye from the murex trunculus. Sepia officinalis In 1887, Grand Rabbi Gershon Henoch Leiner, the Radziner Rebbe, researched the subject and concluded that Sepia officinalis (common cuttlefish) met many of the criteria. Within a year, Radziner chassidim began wearing tzitzit with cuttlefish dye. Herzog obtained a sample of this dye and had it chemically analyzed. The chemists concluded that