claspers is a form of:

Regression



noun
1.
(a backward movement, a retreat, a return to an earlier stage of development) ការថយក្រោយ, ចលនាថយ, ការដើរថយក្រោយ, ថយ, ដំណើរត្រឡប់ទៅកន្លែងដើមវិញ
ENGLISH MEANING
noun
1.
The act of passing back or returning; retrogression; retrogradation.