Capsid decoration protein which helps to stabilize the capsid against extremes of pH and temperature. Once maturation and expansion of the capsid has occured, trimers of soc attach the interfaces between the hexamer of the major capsid protein. Acts as a 'glue' between neighboring hexameric capsomers. Dispensable for the head morphogenesis and phage infection. Homotrimer. Interacts with the major capsid protein; three soc molecules associate with each interface between the major capsid protein facets. 870 copies decorate the capsid. Belongs to the Tevenvirinae Soc family.