The search involves wide-area scanning of the zone determined to be the final resting place of MH370. Once the wide area scanning is completed, data is analysed to find seabed zones or features that are "interesting", or which appear to need much closer examination. The Fugro ships then go over the sites identified, that need closer examination, with a more intensive scan.
Sometimes, natural features are discovered that resemble the aircraft wreckage - that upon closer inspection, are found to be just that - natural features.
The defined search zone contains seabed features that were previously totally unknown, despite previous deep-ocean satellite imagery of the seabed. That satellite imagery was found to be seriously lacking in detail.
Seabed features found in the intensive MH370 search include volcanoes, 1400 metre deep canyons, and a wide range of seabed conditions ranging from deep sediments to sand. Just recently, the search involved a closer look inside an extinct volcano crater.
No doubt, the deep trenches in the zone around the Broken Ridge underwater feature are "challenging" for the searchers. This Broken Ridge area is where searching has been concentrated.
The intensive scanning and data-processing produces the equivalent of a good B&W photo of the seabed, in the area scanned in detail.
Geoscience Australia is just one of the Australian Govt's scientific arms that is assisting extensively in the search for MH370, and more information about the MH370 search can be found on the Geoscience Australia site.