In Castlevania: Harmony of Despair for the Xbox 360, there is a hidden item in each chapter that will boost your end score when you collect them.
The Bell is hidden in Chapter 1. Look for a room with three bells. Slide under the lowest one and jump up into it to make the hidden item appear.
There are six hidden items to collect, so check out my guide to find the other hidden items in Castlevania: Harmony of Despair.