Example of more nodular basalt or basaltic andesite seen during the seventh dive of the Seascape Alaska 3 expedition showing hard, well-cemented, rounded knobs (clasts?) with sand interspersed between the knobs and a diverse biologic community flourishing on the rocks.
Rocks
Image courtesy of NOAA Ocean Exploration, Seascape Alaska. Download larger version (jpg, 1.3 MB).

Example of more nodular basalt or basaltic andesite seen during the seventh dive of the Seascape Alaska 3 expedition showing hard, well-cemented, rounded knobs (clasts?) with sand interspersed between the knobs and a diverse biologic community flourishing on the rocks.