“Anionic H-Bonds” Structure Two Simple Bilayers, One Natural Living membranes consist of bilayers of primarily anionic polar lipids. We describe two simple, single-chain lipid bilayers: pure oleate C18Δ9 carboxylate, and a chlorosulfolipid (CSL), a C24, hexachloro-1,14-disulfate, from the fresh water (pH 4.3) alga, Ochromonas danica. Oleate bilayers are formed either from Na-oleate or from micelles of oleic acid. Both monolayer headgroups, carboxylate and sulfate, trap a H+ between their oxyanion pairs, (“anionic H-bond”). In an aprotic medium they have strong H-bonds (<=20 kcal/bond), analogous to the maleate anion (JACS 2015, 137, 5730). The maleate anionic H-bond is stabilized by ring strain; here van der Waals interactions between the thin methylene chains, together with the bulk of both headgroups, compacts oxyanions forming the anionic H-bonds. O. danica's CSLs’ sulfates, at C1 and C14, form two sulfate sheets, one at C1 between headgroup pairs and the other at C14 in the low dielectric domain. There aren’t other lipids nor proteins in the O. danica surface bilayers. Thus each bilayer has four sulfate sheets, two at C1,C14. Computations show that chloro groups bond hydronium ions at near covalent bond strength in a hydrophobic domain. Inside each monolayer, the C14-sulfate sheet creates a negative field deep in the bilayer. Two chloros are on C2 adjacent to the C1-sulfate surface. They attract hydronium ions to the surface bilayer, each brings water and H+ to the C14 sulfate sheet. Water stabilizes the sulfate sheet and H+ forms anionic H-bonds between sulfates. These four strong sheets protect O. danica from osmotic bursting as do walls in prokaryotes.