These soft, gray seeds are from the Mgambo Tree, Majidea zanguebarica, native to tropical Africa and grown ornamentally on Nevis. Their texture is pure velvet -- hence their nickname -- but they are also know as Black Pearl Seeds in Hawaii where they are very common, and often mistakenly referred to as Pussy Willow in Nevis.
The Mgambo Tree is small and nondescript, except when the fruits split open to reveal their bright red/fuchsia interior and seed treasure. These fruit pods are used in dried floral arrangements, wreaths and potpourri, while the seeds are commonly used in jewelry. The wood of the Mgambo is hard and fine-grained, valued in cabinetry. Botanically it belongs to the soapberry family, its close relatives being the litchi, rambutan, longan and soapberry. "Mgambo" is a Swahili word meaning "announcement" or "proclamation," which the tree makes loudly when its fruits mature.