it was a well-known synthetic dye "Prussian blue" made by reacting Iron(II) sulfate with an organic material. In this case, the cuttlefish only supplied the organic material which could have as easily been supplied from a vast array of organic sources (e. g., ox blood). Herzog thus rejected the cuttlefish as the Ḥillazon and some suggest that had Leiner known this fact, he too would have rejected it based on his explicit criterion that the blue color must come from the animal and that all other additives are permitted solely to aid the color in adhering to the wool. Janthina Within his doctoral research on the subject of Tekhelet, Herzog placed great hopes on demonstrating that Hexaplex trunculus was the genuine Ḥillazon. However, having failed to consistently achieve blue dye from Hexaplex, he wrote: “If for the present all hope is to be abandoned of rediscovering the Ḥillazon Shel Tekhelet in some species of the genera Murex [now "Hexaplex"] and Purpura we could do worse than suggest Janthina as a not improbable identification". Janthina is a genus of sea snails, separate from Hexaplex. More recently, blue dye has been obtained from Hexaplex and the pigment molecule itself is hypothesized to be Tyrian Purple or Aplysioviolin. Janthina seems an unsuitable candidate in several ways: it was apparently only rarely used by ancient dyers; it is found far out at sea (while the hilazon is apparently found near the coast); and its pigment is allegedly unsuitable for dying. In 2002 Dr. S. W. Kaplan of Rehovot, Israel, sought to investigate Herzog's suggestion that Tekhelet came from the extract of Janthina. After fifteen years of research he concluded that Janthina was not the ancient source of the blue dye. Current status of the tekhelet commandment A midrash states that tekhelet was "hidden" (נגנז) and now only white strings are available. According to the Sifrei, tekhelet is hidden until the next world. The meaning of the term "hidden" is unclear. Beit Halevi argued (when debating the Radziner rebbe) that a continuous tradition regarding the source of the dye, which no longer exists, was necessary in order for it to be used. However, Radbaz and Maharil ruled otherwise, that rediscovering the dye is sufficient to perform the commandment. Yeshuot Malko suggested that even if tekhelet was hidden until the messianic era, the apparent rediscovery of tekhelet suggests that the messianic era is approaching, rather than