In the drumming and singing that accompanies Yoruba orisha worship and its Afro-Brazilian continuation in Candomble, the agogo's job is not to carry melody or to stand out as a solo voice but to hold down a fixed, repeating bell pattern that everyone else, drummers, singers, and dancers, organizes their own rhythm against. Ethnomusicologists call this kind of part a timeline, and it is a defining structural feature of a wide swath of West African and Afro-diasporic music, sacred and secular alike, not unique to religious contexts but essential within them: without a steady timeline, the interlocking, often deliberately displaced rhythms of the drum ensemble have nothing to lock against.
The agogo's own construction supports that function well, one or two metal bells of slightly different pitch joined by a handle, struck with a stick to produce a bright, cutting tone that carries clearly over drums and voices without being swallowed by them, exactly the acoustic profile a timekeeping part needs in a dense musical texture. A ceremony's lead drummer typically listens for the agogo pattern before committing to an improvised phrase, treating the bell rather than any single drum as the ensemble's true anchor.