An important function of symbiont-bearing benthic foraminifera is to provide their endosymbiotic microalgae with light. At the same time, these foraminifera have to resist hydrodynamic forces. Foraminifera match these demands by constructing shells (tests) functioning as glasshouses. In shallowest regions of oligotrophic tropical seas, at the one end of the scale, foraminifera with spherical and thick lenticular tests develop special fixing .....