Serpulæ and Sabellæ.
1, 2 SEA-URCHIN'S TEETH (Two illustrations.)
3 COMMON SEA CUCUMBER
4 COMMON RAZOR-SHELL
5 COMMON SERPULÆ, attached to a piece of stone.
XXII.
With the exception of the Balani (Acorn-Barnacles), perhaps the most common objects to be met with at the sea-shore are the Serpulæ. Scarcely a rock, or shell, or bit of old china, or piece of wood, or rusty nail, lying near low-water mark, but is encrusted with colonies of these animals. I have a small twig of a tree by me, so thickly coated with Serpulæ as to obscure all signs of its ligneous character, except at each end. A shell also exhibits the same phenomenon, and well-nigh defies the most skilful observer to define its original form with any degree of certainty.
The shelly tubes of these animals are built in the form of serpents, or twisted funnels, of a milk-white colour. Although so extremely hard, these tubes are formed solely by an exudation from the body of the animal—a simple marine worm. Unlike its erratic friend, the earth-worm, the Serpula is sedentary in its habits, and at no time does it ever leave its dwelling.