Branched Features on the Floor of Antoniadni Crater

In this image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, the dark branched features in the floor of Antoniadi Crater look like giant ferns, or fern casts. However, these ferns would be several miles in size and are composed of rough rocky materials. A more likely hypothesis is that this represents a channel network that now stands in inverted relief.