Along with Mn-phosphorite pavement rocks (see Rocks 2, 3, 4), the other most common rock found on the Blake Plateau is a foraminiferan limestone. Foraminifera are small (.25 to 1.00 mm) planktonic organisms that produce a calcium carbonate shell, or "test." When they die, their tests fall to the seafloor and eventually get buried and cemented, forming foraminiferan limestone.

Collected on JSLII Dive 3463, Barrelfish Cliff, Blake Plateau (2045 ft).