Guardian lions (石獅) go by pairs.
In many cases, the left-hand side lion has a closed mouth (as if it said "UM"), and the right-hand side lion has an open mouth (as if it said "A").
These syllables are derived from the sanskrit expression "A-UM", signifying "the source of everything" and "the ultimate".
In short, such lions reference the Indian origins of Buddhism and have been developed in China. They are associated to Tantric or Esoteric Buddhism (Chinese 秘密佛教 ; Japanese 密佛教 Himitsu Bukkyo / Mikkyo).
This lion was scanned in Xi'an city center, between the Muslim Quarter and the Bell Tower.
