Remnants of an old pillow basalt with cooling margins showing. This was seen on Quinn Seamount during Dive 04 of the Seascape Alaska 5 expedition.
Pillow Basalt
Image courtesy of NOAA Ocean Exploration, Seascape Alaska. Download larger version (jpg, 2.0 MB).

Remnants of an old pillow basalt with cooling margins showing. This was seen on Quinn Seamount during Dive 04 of the Seascape Alaska 5 expedition.