After the shell reaches 2½ whorls, the mantle resorbs the columella and septa of all the whorls except the body whorl. As a result, the viscera are no longer arranged in the spiral way usual in gastropods (See 35Mm 35 Myosotella myosotis. Salting on tidal River Dee, Flintshire, Wales. December 2018. )..
1: low ribs are all that are left of the resorbed septa that earlier separated the whorls of the spire.
2: remaining stump of columella.
3: septum separating body whorl from spire (broken during opening of shell, entire when alive; see image 9Mm 09 Myosotella myosotis. 8mm high. Shell cut transversely, and part of spire wall removed to show interior. Salting on Dee Estuary, Cheshire, England. June 1997. for more complete septum).

marinvert.senckenberg.science/image-browse/