The genus existed during the miocene period, in the coralline Crag, under a form closely allied to A. spongites.
Coral of extinct genus, from the inferior or coralline crag, Suffolk.
These coralline forms were mingled with the joints, stems, and occasionally the heads, of lily encrinites.
Where the white "coralline" Crag occurs, the pebble bed lies below it.
They feed on crustaceans, small fishes, and the innumerable marine invertebrates that inhabit the coral reefs and coralline rocks.
They are composed of coralline limestone, nowhere exceeding 200 feet above the sea, and are well wooded and tolerably fertile.
Oftener, also, darker in the coralline than in the volcanic islands.
Both formations are of moderate thickness; the red crag rarely exceeding 40, and the coralline seldom amounting to 20, feet.
It is an organic product, the growth of a whole people the coralline structure builded by a nation.
The third or coralline zone extends to the depth of about fifty fathoms.