Sago is the starch extracted from the spongy central pith of tropical palms, chiefly the true sago palm (Metroxylon sagu) of Southeast Asia and the Pacific. Naturally gluten-free and almost pure carbohydrate, it is sold as flour, damp starch and the small round "pearls" that cook up into glossy, chewy spheres — a look-alike of tapioca, from which it is nonetheless distinct.