In general, there are four ways to tell if your sea moss is past its expiration date or spoiled:

  1. If the color of your sea moss suddenly changes (off color)
  2. If there is a strong musty smell
  3. If the sea moss gel becomes slimy or watery
  4. If you see off-color marks that is actually mold forming near the top of the bottle (usually green) or in the middle of your sea moss (mixture of white and green).

At that point it is best to throw it. Please be sure to at least refrigerate your sea moss at temperatures below 40 degrees and never let it sit out extended periods of time in warm or room temperature.