Secondary spines

The secondary spines are the small spines around the primary spines, distributed all around the test. They are also called scrobicular spines when they are associated with the primary spines. Secondary spines not in the areoles (region around primary spines) are called "Military spines".

The shape of the secondary spine is plastic over the test, depending on where the are situated.

Their main function is not clearly defined, which is however of sideline interest. Based on the SEM analysis, we found that the surface structure (ornamentation) of both species differ. This difference also serves as a distinguishing feature, as depicted below.