Nummulites gizehensis is one of numerous larger foraminifera which from the Carboniferous to the Tertiary contributed to the formation of sedimentary rocks. In the Allgäu, Bavaria, nummulitic limestones are exposed. Recent larger foraminifera occur, like their fossil allies, in warm shallow seas. Upon their death, their shells turn into marine sand. This is illustrated by a Hawaiian sandy beach. The sublittoral algal benthos of a Hawaiian rockpool is a habitat of these sand producers. Here Sorites variabilis, Amphistegina lobifera, Amphistegina lessonii, Peneroplis pertusus and Heterostegina depressa occur the ecology of which is treated in the film. In the interstice of the algae they are protected against surf and solar radiation.