Ooid Cross Section
An ooid cross-section describes a lens-shaped or biconvex profile — widest at the center and tapering toward the edges — used by anonymous Marine whistleblower "RB" to characterize the cross-sectional geometry of the disc-shaped craft he claimed to have guarded in December 1963. An ooid is a small rounded grain with concentric layers, but in geometric usage the term describes an oblate ellipsoidal form. In craft-description terms, this corresponds to what is commonly described as a "hamburger-shaped" or classic flying saucer profile: a flattened disc that is taller in the center than at the rim.
RB described the 40-foot craft as totally symmetrical with this ooid cross-section, silverish in appearance and resembling polished aluminum, with no visible seams except for a hatch seam on the lower portion. The geometry is consistent with many classic UFO descriptions in the historical record and with the "sports model" disc described by Bob Lazar in the context of S-4 at Area 51.