In structures of complex natural products, the assignment of absolute configuration (AC) of remotely located stereocenters (separated by five or C-C bonds) is problematic. The structure of the new glycolipid, axinoside-1 (1), isolated from a Western Australian axinellid sponge, comprises a tetrasaccharide linked to a complex C28 aglycone, 2: the first in its class. Classic linkage analysis of the sugar moieties in 1 by COSY, TOCSY-HSQC and HMBC defined the stereochemistry and regiochemistry of the glycosidic bonds, but the highly-oxygenated C28 aglycone 2 presented its own challenging problem; how does one complete stereoassignment of the four asymmetric carbons, each disparate from the rest? Here, the complete stereostructure of 2, including AC, is solved. A biosynthetic hypothesis explains the oxidation pattern of 2 – PKS-like C2 ketide extensions with skipped DH-ER domains and Cyp450 hydroxylation at C4.