Clean the test
The first steps were made, and all the observed features were stored for further examination.
The next step involves a quite dangerous chemical agent, so please wear safety goggles and gloves.
From spiny to shiny...
...step by step
With a hydrogen peroxide solution (30%) you dissolve organic tissue which facilitates the removal of all surface components (which you obviously also store for further examination).
Underneath lays a fascinating and beautiful structure which emphasizes the structural growth of the sea-urchins.
But now, it seems to be even more difficult, to distinguish between the two species.
But it enables us to gain access to the intestines of the sea-urchins. This might lead us to further conclusions.