Search crews hunting for Malaysia Airlines Flight 370 in the desolate waters off western Australia have discovered a shipwreck lying deep below the surface.

The Australian Transport Safety Bureau said Wednesday that the unexpected find came when sonar equipment on board one of the search vessels detected a cluster of objects nearly 4 kilometers (2.5 miles) below the surface of the Indian Ocean.

A closer inspection revealed that the debris field was likely man-made, so crews sent down a camera to see what it was. An analysis of the photos this week revealed that the objects belonged to a previously uncharted shipwreck.

Marine archaeologists are now examining the photos to see if they can identify the ship.