I found Frontona depressa in moss samples from trees in the years 2021, 2024 and 2025. This is the typical habitat of this ciliate, just as Kahl (1931) also described it. A typical characteristic, in addition to its small size and habitat, is the position of the contractile vacuole, which lies below the cell equator. It has only one excretory pore (s. fig. 7). At the posterior end there are some elongated cilia (s. fig. 6), which can also be clearly seen in free-swimming specimens (s. fig. 1 b). The preoral and postoral sutures (s. fig. 5) are only weakly developed in Frontonia depressa. I was only able to discern them faintly. According to my measurements, the spindle-shaped extrusomes are 4.2–4.9 µm long (s. fig. 8).

Most specimens in my populations were colorless and transparent, without food vacuoles. A few specimens had filled food vacuoles with spores of plants or fungi (s. fig. 1 a-d). Sometimes storage crystals could also be seen in the posterior third of the cell (s. fig. 6).