Mt. Popacatapetl erupting in Mexico. Formed from shells and skeletons of marine creatures. As a result, their distribution is controlled by climatic and environmental processes. I can't identify from the image. Foraminifera are single celled organisms, relatives of Amoebas, that produce chambered shells usually made of Calcite.
Foraminiferal oozes are seafloor oozes primarily formed of planktonic foraminifera.
This is a living planktonic foraminifer. Note the delicate spines covered in protoplasm during life. These are common in planktonic foraminifera, but are rarely preserved in fossils, and are not present at right. These are fossil planktonic foraminifers. The photo was taken with a Scanning Electron Microscope.