Sea urchin

Sea urchins are marine animals of the class Echinoidea, echinoderms that have a soft body enclosed in a round, symmetrical, calcareous shell covered with long spines.

When eaten as sushi, they are often served with quail egg. Winter is considered the best season for them. The best quality sea urchin sushi is taken directly from a live animal, rather than being frozen. The west coast of the United States is one of the world's leading sources.