This is the coral stone ornament on the east side of the royal garden "Tianyimen". Coral ornaments are also called "sea cucumber stones" because they are piled up by coral individuals shaped like sea cucumbers.

Sea cucumber is rich in longevity and immortality, which means immortality. Qin 'an Hall behind "Tian Yimen" is dedicated to the northern Taoist "Zhenwu Emperor". Immortality coincides with Taoist thought of health preservation.