Could A Lump On Finger Be Calcium Deposit?

Hi, I'm 14 and when I was 8 I was shot with a pump powered BB gun. I was hit in the right pinkie. I got the BB out of my finger but a round dime sized ball was left in my finger, I dont know if it grew over time or if I got it when I was hit but I was told it is a calcium deposit, I'm not a doctor so I don't know what it it. I can move it side to side in my finger only an inch or 2 and it is a dark blue and black color. Do you have any idea what it could be?