Because of their small size, <100 µm, microforaminifera were usually overlooked by protozoologists, marine biologists and micropaleontologists. Karl Grell's pioneering work on this group, in the 1950's, demonstrated its great potential for the study of the biology of foraminifera. However, only recently has the scanning electron microscope given us the means to study the tests of these minute foraminifera. They are a very diverse and abundant group. In this paper we present a general overview of various aspects of microforaminifera, including detailed description of the family Rotaliellidae, and some perspectives for future studies.