First steps

We begin with a visual observation by placing the sea-urchin under the binocular. By critically examining every feature we see, we get familiar with this strange form of life and we loose our fear of the unknown deep sea creatures.

This sample was kept in 70% ethanol. It's surface components are not so fragile, and the handling of the test is facilitated.

This individual was dried at the fresh air. The surface components are extremely brittle and delicate, handle with care.

Based on these four pictures of both individuals, you have to decide which features could be of particular interest. Which differences can you observe? Which features do you think will help you distinguishing between the individuals and eventually lead to the identification?