Dark matter asteroid
From Memory Alpha, the free Star Trek reference
A dark matter asteroid is an object composed of dark matter, that emits electromagnetic radiation.
In 2376, a graviton ellipse being investigated by the USS Voyager was attracted to a dark matter asteroid. The two anomalies collided, causing severe gravimetric distortions inside the ellipse that caused damage to the Delta Flyer. (VOY: "One Small Step")
