A search party has found the main wreckage of EgyptAir Flight 804, which crashed last month, at the bottom of the Mediterranean.

On May 19, the Airbus A320 crashed while en route from Paris to Cairo, killing all 66 people aboard. The cause is currently unknown. Finding the main wreckage, which is under 10,000 feet of water, is vital to understanding what happened.

The plane itself could yield clues—burn marks or chemical traces from an explosion, for example—but the real key is that the jet's black boxes are likely to be in the vicinity, since they would have sunk with the bulk of the plane. The cockpit voice recorder and flight data recorder contain two hours of audio recording from the cockpit and dozens of datapoints from the entire flight, including altitude, airspeed, and heading, along with the positions of individual controls and flaps at any given moment. Built to survive just about anything, they can paint a vivid picture of the plane's final moments.

This discovery came just in time: The black boxes carry locator beacons that ping for about 30 days–only one more week in this case. Once those turn off, finding anything at the bottom of the ocean becomes a daunting task. Just ask the folks who are still looking for MH370.