This section is from the book "The Steward's Handbook And Guide To Party Catering", by Jessup Whitehead. Also available from Amazon: Larousse Gastronomique.
"Another radiate, and the only other one of this class that I know to be eatable, is the Echinus - the sea-urchin, or sea-egg. This animal carries a system of channels and membranes in a hollow globe of flinty, but brittle texture, covered by spines, like a miniature hedgehog well rolled up. Examine one when it holds no eggs, and you will find nothing eatable about it, inside or out. Whatever the season, however, but especially in summer, a large proportion of them will contain several bunches of orange-yellow eggs so minute that the whole contents of a big echinus will not fill a dessert-spoon. These eggs taste like an oyster and are nutritious; they call for no cooking, and are easily got at Thus they have always been fed upon as a relish by half-refined coast people like those of Eastern Asia and its neighboring islands, and by the well-supplied Indians of Puget Sound and British Columbi i, and have proved the stand-by of miserable savages whose desolate homes afford them little else to maintain life.
The Neapolitan poor are not as a rule dainty, but, while delighting in sea-urchin, they look down with scorn upon the Calabrese, because they cat sea-slugs, which, if properly cooked, are not very bad".