Planispiral
Appearance
![](http://178.128.105.246/content-http-upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Anisus_septegyrus1pl.jpg/220px-Anisus_septegyrus1pl.jpg)
Planispiral is a condition in which a tubicolous shell is coiled in a single horizontal plane and the diameter increases away from the axis of coiling. This term is usually used for describing gastropod shells. Many cephalopods and tubeworms can also have a planispiral shell (Allaby and Allaby, 1999).
References
[edit]- Allaby, A. & Allaby, M. (1999). "Planispiral". A Dictionary of Earth Sciences. Retrieved 2014-01-13.