These odd shaped angular corky nuts are a very common drift seed on the beaches of Borneo. The nuts have frequently been gnawed by rats to get at the seed inside. These nuts originate from two very similar mangrove trees with very large fruits. This article concerns Xylocarpus granatum which has the largest fruit. See also our article on Xylocarpus moluccensis. The nuts of both species are the same size and impossible to tell apart.
Each fruit is covered by 4 (occasionally 5) tortoise like shells. The largest fruit can reach 25cm diameter and contain 8 to 20 nuts.Xylocarpus granatum fruit photographed growing on an outlet drain near the Empire resort in Brunei Darussalam, Borneo. Xylocarpus granatum is a common component of the mangroves that grow around Brunei Bay. Xylocarpus granatum fruit grow to a maximum of 25 cm diameter. The smaller fruit of Xylocarpus moluccensis reach a maximum of 11 cm diameter and contain fewer nuts.