Large, dark, rounded volcanic rocks form a heavily textured mound on the deep ocean floor.
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Volcanic Rocks
During Dive 01 of the 2026 American Samoa ROV + Mapping Exploration expedition, volcanic rocks, likely columnar basalts, were seen as the remotely operated vehicle moved from the explored seamount’s caldera up to a ridge feature. These rocks provided hard attachment surfaces for animals such as the stalked glass sponge seen extending into the water column in this image.
Credit

NOAA Ocean Exploration, 2026 American Samoa ROV + Mapping Exploration