Back when I was a kid and used pencils a lot there were the normal number two pencils, the fat pencils, and a few mechanical pencils. They all used hard pieces of lead than always seemed to break during a test.
Sharpie has evolved pencil tech with a new liquid graphite pencil that takes tech from pencils and pens and mashes it together for an entirely new animal. The Liquid Pencil looks like a pen more than a pencil, but it is erasable.
According to Sharpie it writes as smoothly as a pen, can be erased like pencil lead, and is permanent after three days on a page. This is cool, I wonder if the liquid graphite is number two equivalent. You can reportedly get a pair of them and six erasers for $5.