Harmony Bell?

Anybody heard of them? My mum bought me one and it's a tiny little bell (and I mean tiny, not like a cows bell lol, you can only very faintly hear it under your clothes) you wear on a long chain so it sits on your tummy area and baby supposedly can hear it throughout the pregnancy. The idea is that once the baby is born you can hang the bell in the nursery and the tiny tinkling noise is associated with the warmth and safety of the womb and can help soothe the baby....