Planorbis planorbis is very common freshwater snail in western part of Eurasia.

It holds its shell upside down and its shell is sinistral as in all other Planorbidae. Apertural view of a shell with a live snail in it:

Dorsal view of a snail and umbilical view of its shell:

Apical view of the shell and foot of a snail. The sun was shining brightly on the snail so there are some internal anatomical features visible. (This one photo is unaltered, while there are adjusted levels on other photos.)

If I undersnad it correctly then there is clearly visible renal vein as a thick red-brown line inside the last whorl. The renal vein leads to the kidney (that starts with renal tube). I think, there is also air chamber visible. I think, that the dark line insie whorls is inestine, that is connected to the stomach (the most dark place in the penultimate whorl):

There is visible a mantle border on the photo:

A similar photo:

References

There are anatomical images of the genus Gyraulus by Meier-Brook available. These images are also reproduced in other malacological books because it shows the whole anatomy of the animal (removed from the shell).

Meier-Brook C. 1983 “Taxonomic studies on Gyraulus (Gastropoda: Planorbidae)”. Malacologia 24(1-2): 1-113. page 30.

Some anatomical images exactly of Planorbis planorbis were made by Baker, but they are not clearly undestandable without detailed anatomical knowledge.

Baker F. C. 1945 The molluscan family Planorbidae. The University of Illinois Press, Urbana.