There is, furthermore,

the genus of the sea-nettles, peculiar in
its way. The sea-nettle, or sea-anemone, clings to rocks like
certain of the testaceans, but at times relaxes its hold. It has no
shell, but its entire body is fleshy. It is sensitive to touch, and,
if you put your hand to it, it will seize and cling to it, as the
cuttlefish would do with its feelers, and in such a way as to make the
flesh of your hand swell up. Its mouth is in the centre of its body,
and it lives adhering to the rock as an oyster to its shell. If any
little fish come up against it it it clings to it; in fact, just as
I described it above as doing to your hand, so it does to anything
edible that comes in its way; and it feeds upon sea-urchins and
scallops. Another species of the sea-nettle roams freely abroad. The
sea-nettle appears to be devoid altogether of excretion, and in this
respect it resembles a plant.