In the Zira’at, the congregational mosque of the abandoned town of Old Sima on the island of Nzwani, there was once a large rectangular four-legged basin carved from chlorite-schist, a metamorphic stone found on the east coast of Madagascar, which was used for washing before prayers. In the modern village of Sima, I was told the following story regarding the origin of this basin: ‘One day, a woman of Sima was foraging on the reef for fish and shellfish. She saw a strange boat, from which a demon called to her and said “My baby is ill, and needs medicine from the forest. I am of the sea and know nothing of the land. You are a land person, and know the plants of the forest. If you go to the forest and bring the plants my baby needs, I will give you a gift”. The woman went into the forest and returned with the necessary plants, the baby recovered, and she was given the magical basin, which has remained in Sima to this day’ (Ahmadi Bourhane, Sima, personal communication 1984; cf. Hébert 2000). Indeed, 30 years ago, one could see the fragments of the now-broken basin near the Zira’at. This story emphasises the widespread dualism of the land people and the sea people, different and yet interdependent, and connects the ‘sea people’ to Madagascar through the datum of the chlorite schist basin.