Silicoflagellates are one of three microfossil groups that have skeletons made up of a rigid latticework of rods. Mathematical modeling of silicoflagellate skeletal design suggests that an important factor influencing skeletal shape is the minimization of apical surface area, while the reduction of skeletal material appears to have secondary importance. Presumably, minimization of area is also important for the radiolarians and ebridians, which are the other groups having latticework skeletons. The reason why these three groups use such a skeletal design, and why this morphology is not found among non-silicate groups, remains a mystery.