Siliconitrifiers
With the rise of Nitromethanians, which produced abundant methane, the Siliconitrifiers also arose to make use of this abundant methane source for their silicone resin coatings. They were swiftly exposed to the ammonia which was also produced by the Nitromethanians, and in response they became nitrifiers—using some of the oxygen they produce to oxidize ammonia into nitrite. This has resulted in them having less leftover oxygen to form their silicone resin coating, but as they live in oxygen-poor environments with comparatively few predators this is not an issue. Like their ancestor, they have specialized organelles for processing silicon and creating silicon compounds, and they enter a dormant cyst form when no methane is available.
Siliconitrifiers are found mainly in oxygen-poor habitats with access to at least some sunlight, such as just below the surface of soil, sand, and mud, or in decaying flora. As far as decaying flora goes, they have a notable preference for species which make use of silica. Their choice of habitat grants them easy access to the methane and ammonia produced by Nitromethanians. Terrestrial soil-dwelling species, when exposed or when their soil dries out, are protected from desiccation by thicker cell membranes and a slightly thicker resin coating. Like with many Terran microbes, individual species are difficult to distinguish. They all just look like blobs.