Oblate spheroid seed pod, brown, with black "skin", not quite 3 inches in diameter with a little more than 1 inch axis (thickness through its center) in deteriorated condition.
Tropical insular coastal valley.
Spotted on the ground along the trail to the falls in Waimea Falls Park. It had obviously been there for a while. There were many tall trees in the vicinity, so it was not possible to determine from which one the pod had fallen. In appearance, despite its being black/brown rather than orange, the pod immediately reminds one of a tangerine, and is of similar size. Imagery note: Unfortunately, the focus of the "overhead" view (the first image above) is poor.