The Hemiaulus diatom found in Late Jurassic-Early Cretaceous amber from Thailand. A. Photograph of specimen within dark amber matrix. B. Interpretative drawing of the photograph. Scale bar represents 10 µm. We can clearly distinguish the central parts of the frustule and its typical elevations. They end with spines corresponding to the linking apparatus of the frustule. The black arrow on A indicates the hyaline marginal ridge.