Underwater view of a rocky ocean floor with textured gray rocks, smooth boulders, and fragmented pieces, illuminated by dim light.
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Sediment Sheets
Ancient lava pillows (left) and ferro-manganese-encrusted rocksheets (right) seen during the latter part of Dive 13 of the 2026 Cook Islands ROV Exploration cruise. These sheets may be remnants of ashfall from ancient volcanic activity.
Credit

NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration