The characteristically indented, sub-spherical shell is about 100 μm long. The outer wall is perforated by circular pores of similar size, which are surrounded by weak to strong frames. A double spiral can be seen which forms three widely spaced whorls, including the outer shell. Widely spaced beams connect the whorls internally and a few may project as short, scattered spines in a irregular distribution on the shell surface. The pylome is clearly visible, forming a tube with rather long teeth.