How do the phospholipids in archaea differ from those in other cells?

Archaeal phospholipids lack fatty acids, but instead have derivatives of the hydrocarbon isoprene linked to the glycerol backbone. Isoprene units linked via an ether bond whereas the phospholipid in other cell membranes contains glycerol backbone with a phosphate and 2 fatty acids. Fatty acids are linked via an ester bond.