Climacosphenia scimiter, all from GU52X-1 A colony of living cells on branched mucilage stalk B valve and valvocopula of cleaned material, LM-DIC, showing consistently narrow craticular bars C, E valve in phase contrast LM, showing more strongly silicified basal pole in C and weakly silicified apical portion in E, along with difference in stria density; note appearance of annulus at basal pole (arrow, C) D basal pole in SEM, oblique view, showing shallow mantle and very weak costae and apparently discontinuous annulus. Scale bars: 50 µm (A, B); 10 µm (C–E).