Has an important morphogenetic role. Involved in the assembly of at least five coat proteins, including CotB, CotG, CotS, CotSA and CotW. Required for appearance of a morphologically normal outer coat. To a large degree, CotO and CotH act at a late stage of coat assembly from within the outer coat to direct maturation of this structure. Localized in the outer spore coat. Largely but not entirely controlled by CotE.