These are the most common collectible you will come across. They are numerous, over 900 of them exist in fact, but they are easily spotted due to their glowing blue color which contrasts with the red of Hell. There are two types of Soul Orbs.
There are 2 type of clusters, blue which are the more common and pink, Upon touching the cluster, 4 smaller ones will appear in the direction the plume was pointing. You must quickly pick up all 4 in order to obtain any. Should you fail, the cluster resets and you must touch the original pink one again.