A close look at the inside of a pillow tube seen during Dive 07 of the second Voyage to the Ridge 2022 expedition at 3,167 meters (1.97 miles). Basalt "pillows" form when lava cools quickly under water.
Pillow Tube
Image courtesy of NOAA Ocean Exploration, Voyage to the Ridge 2022. Download larger version (jpg, 1.7 MB).

A close look at the inside of a pillow tube seen during Dive 07 of the second Voyage to the Ridge 2022 expedition at 3,167 meters (1.97 miles). Basalt "pillows" form when lava cools quickly under water.