9 letters · 23 points in Scrabble
noun a powerful neurotoxin produced by certain dinoflagellates found in red tides; it can accumulate in mollusks that feed on the dinoflagellates and cause food poisoning to humans
originFrom Saxidomus giganteus (butter clam), from which it was first isolated + toxin.
Etymology from Wiktionary, CC BY-SA 3.0