The palolo worm (the reproductive section of a polychaete worm) is a favorite delicacy that swarms the surface of the sea once or twice a year in Samoa. During the swarm, Samoans wear necklaces made of mosoʻoi flowers and use the fragrant flowers to attract the palolo to the their boats. Then, they use hand nets to scoop them up.

Because the palolo harvest is such an important event, Samoans carefully observe the environment for signs that the swarm is approaching. Some believe that palolo start swarming when the mosoʻoi tree flowers, or when a strong smell comes from the reef, or with changes in the weather, such as strong thunderstorms. A common way to predict the swarm is to observe the moon. Predictions are based on the date of the three-quarter moon, sometimes called the last quarter moon:

If the last quarter moon occurs on... 

• October 1 to 8—palolo will not come until November.
• October 8 to 18—palolo will not come in October or there will be a very small swarm in October followed by a stronger swarm in November.
• October 8 to 18—palolo will not appear in October or the swarming will be weak followed by a stronger appearance in November.
• October 19 to November 7—there will be a single strong swarming during this time period.
• November 8 to 17—there will be a strong swarm during this time period (Craig 2009).