Sterling filigree heart caged a harmony brass pendant. A part of Mayan culture, the Bola necklace, harmony bell or angel caller is based on an ancestral design, and consists of a locket housing a small and subtle chime that rings quietly whenever it is moved. The necklace is ideal for aiding relaxation, but is also noted for being a necklace that an expecting mother should wear so that her baby might hear the relaxing chimes too.