The material in the Western Church was, as a rule, stone, frequently porphyry, or other rich marbles. In the Eastern Church the font was usually of metal or wood, and seldom or never possessed any beauty (Neale, Eastern Church, 1:214).
The usual form of the font was octagonal, with a mystical reference to the eighth day, as the day of our Lord's resurrection, and of regeneration by the Spirit (comp. Ambros. Epist. 20, 44). The piscina is sometimes found of a circular form, and is occasionally, though very rarely (as at Aquileia) hexagonal. Gregory of Tours (De Glor. Martyr. lib. 1, c. 23) speaks of a font in the shape of a cross, in Spain. The form of a sepulchre is stated to have been sometimes adopted, in allusion to the Christian's burial with Christ in baptism (Ro 4:4).
The piscina usually formed a basin in the center of the baptistery, rather beneath the level of the pavement, surrounded with a low wall. It was entered by an ascent and descent of steps. According to Isidore Hispal. (Orig. 15:4; De Div. Oq.: 2:24) the normal number was seven; three in descent, to symbolize the triple renunciation of the world, the flesh, and the devil; three in ascent, to symbolize the confession of the Trinity, and a seventh, "septimus... qui et quartus," at the summit of the enclosing wall, for the officiating minister to stand on. But the rule concerning the number was not invariable. At Nocera, the number of steps is five, two in ascent, and three in descent. The descent into the piscina of St. John Lateran is by four steps.