Light micrograph of a group of fossil shells belonging to the order known as Foraminifera. It comprises unicellular protozoans whose shells form an important component of chalk and of many deep sea oozes. They live in the sea or salt-water lakes. Their shells are composed of several chambers which are usually penetrated by pores through which the cellular contents (protoplasm) are extruded. Magnification: 28x at 35mm.