Multi-tissue structure that is the filtration unit of the pronephric kidney. A glomus is a glomerulus that spans more than one body segment. It is the vascularized filter of the pronephric kidney. Blood is filtered through the glomus and the filtrate deposited into the coelom early in development, or the nephrocoel later in development. The glomus contains podocytes with well developed foot processes that are anatomically indistinguishable from the podocytes of adult glomeruli. The two glomera are linked via a narrow bridge called the glomeral nexus.