We quantified spatial and temporal patterns of brominated pyrrole variation in the common marine hemichordate worm Saccoglos5u5 kowaJevskii. Using fast·atom bombardment mass spectrometry we found a novel sodium sulfamate salt (C4HBr3N03SNa) of 2,3,4-tribromopyrrole (TBP) that predominated over 2,3,4-TBP (II % vs 0.6% ash-free dry wt). There was no relationship between the total amounts of the 2 compounds. The sulfamate salt was concentrated in the hepatic region (50 %), a possible site of synthesis or storage. 2,3,4-TBP was highest (1.5 'Yo) in the proboscis and tail, which are exposed to predation. No seasonal pattern was apparent for the sulfamate salt over a 30 mo sampling period. 2,3,4-TBP exhibited temporal inCTeases, possibly associated with spawning. The sulfamate salt was not detectable by GCIMS techniques, raising the possibility that sulfonati.on may be more common than realized. The sulfamate salt may serve as the non-autotoxic stable precursor to the more volatile 2,3,4-TBP.