Wikipedia
Planispirillinidae
Planispirillinidae is a family of living Foraminifera and the only one of the Involutinida now living.
The included genera are characterized by asymmetrical, semiinvolute to partially evolute, aragonitic tests consisting of an undivided planispiral or trochospiral tubular chamber wound about the proloculus, or initial chamber. The unbilical region on one or both sides is filled with lamellae. The aperture is a simple opening and the end of the tube.
The genera Alanwoodia and Planispirillina are included in the Spirillinidae in the Treatise, Part C, 1964. The other two were added subsequent to publication.