While archaea are prokaryotes like bacteria, they have some key differences, including their cell membranes.

Here's what makes archaea unique in this regard:

* Lipid structure: Archaea have unique lipids in their cell membranes. Instead of fatty acids like bacteria and eukaryotes, they have isoprenoid chains linked to glycerol by ether bonds. This structure makes their membranes more stable in extreme environments.

* Membrane composition: Archaea can have different types of membrane lipids, including glycerol diethers, diglycerol tetraethers, and others. This allows them to thrive in diverse conditions, such as high temperatures, high salt concentrations, and acidic environments.

So, while both archaea and bacteria lack a nucleus and other membrane-bound organelles, their cell membranes have a distinctive structure and composition.