Possible Clues:

• Seaweed superfood
• Algae rich in iodine
• Algae from half of lake unexplored up in the middle
• Sea urchin's snack
• Oceanic source of iodine
• Marine vegetation
• Large seaweeds with leathery fronds
• Marine growth rich in iodine
• From nickel, potential source of iodine
• Brown algae