They come in a box from which you can only remove one pencil at a time. You then sharpen the pencils with a sharpener built into the box. This collects the shavings so that, once the supply of pencils is exhausted, the box can be used as an urn for the remains.
It's all rather morbid to say the least, but I suppose the idea is an artistic person can use the carbon from your remains to create a body of drawings as your monument. A graphite on paper headstone. Add to that the notion that the box of pencils has a sort of a life of its own, starting out full and dwindling down to nothing but shavings, and you have an interesting reflection that physical things are born, worn down, and reborn again as something else. Meanwhile the drawings, the artifacts of the wearing down process, are something rather more sublime.
Yet, cynic that I am, I couldn't help but think that the quality of the monument created depended on the skill of the hand wielding the pencil. What if the monument ends up being something like Skull and Lemon, pictured above? However, perhaps that's the message -- what is left behind is nothing but shavings and drawings. The shavings can't be helped, but care should be taken in the quality of the art.
By the way, the Skull and Lemon drawing is from a post Real Drawings by Real Artists at redragtoabull. It was drawn by Harry Adams. Lest we laugh at it too much, or perhaps to add to its humor, it sold for