Minecraft wiki entry for Acquiring_a_conduit, associated text: Another way to obtain nautilus shells is via trading with a wandering trader. A wandering trader can spawn anywhere after one in-game day and has a chance of offering a nautilus shell as one of their trades. One nautilus shell costs five emeralds, so obtaining eight nautilus shells require spending 40 emeralds. Despite costing many emeralds, this method is the fastest way to obtain 8 nautilus shells, provided you have a village available as a source of emeralds for trade. However, because the nautilus shell trade is locked after 5 transactions, the player needs to trade with 2 wandering traders that offer nautilus shells to have enough for a conduit, which may take a long time, as not every wandering trader sells nautilus shells.