What was the black hard lump I squeezed out of my leg?

When I was younger I had a lump on my leg which I knew there was something in there so after a few days of squeezing, I squeezed out this extremely hard, wrinkly, dark lump the size of a pea, and now im left with a big scar and dent in my leg. what was it? im not sure if I was bitten or if it just grew? thanks for answering :)