Foraminifera form part of a group of animals called plankton.
Plankton are an incredibly important source of food and foraminifera play an integral role in marine ecosystems.
Foraminiferas consist of a single cell protected by a shell. It is very unusual in the animal kingdom for single-celled organisms to be protected in this way.
Foraminifera create their shells through a chemical reaction with sea water. Sea water contains many dissolved elements including calcium, and dissolved gases including carbon dioxide and oxygen. Foraminifera combine these to make the compound calcium carbonate (CaCO3) in a process called biogenic carbonate production. Calcium carbonate is the common constituent of most sea-shells, limestone rock and the hard parts of a coral reef. Some foraminiferous species however, make a home out of small grains of silica sand that they stick together.
Foraminifera shells are complex and varied and have many chambers. The cell membrane wraps around the hard shell and all the bits of the cell mechanism live inside the shell.
Having a shell inside a cell membrane is also very unusual!
Foraminifera shells can range in size depending on species from around 1mm to over 10mm. Scientists are unsure of the reason for the complex chamber structure