It is usually synonymous with "vesica", a lens shape. The east window consists of three lancets with a vesica above. These are each surmounted by double mouchettes and vesica piscis windows. Organ Opus 118 was installed on both side of the Vesica. The triforium is remarkable for its rhythmic vesica piscis motifs. The two interlocking circles constitute the symbol known as the "Vesica Piscis". In both methods a by-product is the formation of vesica piscis. Another method of drawing a hexafoil is the vesica piscis method. Also, the ichthys symbol incorporates the vesica piscis shape. Furthermore, the unornamented vesica penis points dorsally and bears an evertible toothed bar. The center lens of the 2-circle figure is called a Vesica piscis, from Euclid. The vesica piscis is also used as proportioning system in architecture, in particular Gothic architecture.