Like any organism, archaeal membranes must undergo dynamic physiological processes like fission and fusion during cell division, membrane vesicle budding, or viral entry/egress. However, there is a lack of clarity regarding how archaeal membranes primarily composed of bipolar lipids can undergo fusion (or fission). In a canonical model of bilayer membrane fusion, the outer leaflets of apposing membranes first merge to form a stalk-like hemifusion intermediate. This step is triggered by fusogenic agents like divalent cations, acidic pH, polyethylene glycol, or fusion peptides which help overcome the energetic barriers associated with various intermediate steps along the fusion pathway. In the next step, the inner leaflets merge via transient non-lamellar intermediates to open up a fusion pore and the two membranes completely fuse along with mixing of inner aqueous contents. In the case where GDGT lipids form a monolayer membrane where all lipids are membrane-spanning, there will be high energy barriers and geometrical constraints to forming various fusion intermediates as compared to bilayer membranes. Therefore, we hypothesize that at least some regions of the GDGT membrane should have a bilayer structure which is only possible if some lipids adopt a looping or U-shaped conformation (Figure ).