noun which may take the genitive case particle 'no'
planospiral
Medical term describing a shell or structure that is coiled in a flat plane. Used in anatomical or paleontological contexts.
This fossil has a planospiral shell.
Compound of 平 (flat) and 巻き (winding, coiling), literally 'flat winding'. The exact historical derivation is uncertain; the term is used in modern medical and biological contexts.