The cells are typically found either on their own or in very short chains. When viewed from the girdle side, the cells have a low profile, and the valve surface is curved with a ribbed margin. In water mounts, long tubes known as occluded processes are easily noticeable. These occluded processes are relatively large, varying in number, and widely spaced. The strutted processes feature short external tubes, and there is a ring of closely spaced marginal strutted processes located near the valve margin. Typically, there are four to five processes per 10 µm. In T. punctigera cells, a single large labiate process is present, along with a long external tube.