Rather than bells, these are called "stupas". Besides representing Buddha's possessions (a walking stick, a cup, a plate, and a lotus flower) they also were burial mounds- some important figures wanted to be buried sitting up so a mound in this shape was created (some were also cremated). Early Buddhist stupas included some of the Buddha's own ashes (allegedly). The seated body was said to be still in meditation. One claimed merit of building a stupa was so that the person would not be reborn in a remote location or suffer poverty.