The altar radical on the left marks 祥 as a matter of the spirits - auspicious omens, blessings invoked at the shrine. It anchors the meaning and indexes 祥 with 神 god, 福 fortune, 祝 wish, 祯 lucky, 祺 felicitous - every blessing-character.
羊 supplies the sound yáng → xiáng, a small palatalisation. Sheep were also classic sacrificial animals, so the picture lends a soft semantic flavour: an auspicious offering. The phonetic series 羊 builds 样 shape, 详 detailed, 洋 ocean, 痒 itch.
