Unknown freshwater foraminifer

Remarks: February 2023, I found in material from the Gooimeer, a large freshwater lake in the Netherlands, a foraminifer, unknown to me. Because the lake is a part of the former Zuidersea, which was connected to the North Sea, I thought it was a remnant of that time. After a while I saw granulopodia appear from the shell (Fig. 2), a sign that I had a living specimen for me and also a freshwater species, since the Zuidersea has been closed off from the North Sea since 1932 and has since become a freshwater body. A few months ago I found an empty scale in the same lake.
The granulopodia were only visible for a day. I then mounted the shell in Hydro-Matrix to get a more detailed image of it. The shell seems chitinous (Fig. 4), with a grainy surface (Fig. 8). The narrow sides of the shell are covered with a dense layer of elongated protrusions, rising in size (fig. 5-7). They look like a kind of crystals. They probably cover the whole scale, but they are much shorter on the large surface (Fig. 8). While mounted in Hydro-matrix, the shell broke into pieces due to the pressure of the cover glass. A clog protoplasm became visible with a large number of rod-shaped yellow crystal-like bodies (Fig. 9).

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