The sea urchin in Greece is named achinos (echinoderm) a small spiky sea being. The edible roe is from the female sea urchin and is eaten opened with just a squeeze of lemon. The taste is textural as the roe explodes between your palate and the eggs swim away with twists and turns.
Think about it. The idea of eating food that once you taste it, it takes on a life of its own. Most foods are not made up of millions of particles that separate in your mouth when you take a bite. Its true many foods will separate in your palate but many do not. But when it comes to sea urchin the eggs do explode and enhance the favours as they are cut apart by your teeth.
These sea urchin are natural and taken fresh without any alum which is commonly used in Japan to harden the roe: https://mesubim.com/2013/02/06/4038/