looks like the probe from "Star Trek IV: The funny star trek"
but seriously, if it really looks like that artist's rendering, my first guess would be that its a big chip off a giant rock. Maybe two asteroid collided in interstellar space and this piece has yet to get into the gravitational pull of another object or system.
of course, that theory is based on me looking at a picture and reading the first few paragraphs of one article -- which is how I come to most conclusions in life
Did I mention I have a MIT e-mail address. Instant qualification.