They are simply partners with a reciprocal interest.

The animal-plants sting like nettles; all the monsters without a shell flee from the poison of their tingling organs, and the fragments of their hair burn like pins of fire.

In this manner the humble _paguro_, carrying upon his back his tower crowned with formidable batteries, inspires terror in the gigantic beasts of the deep.

The anemones on their part are grateful to him for being thus able to pass incessantly from one side to the other, coming in contact with every class of animals.

In this way, they can eat with greater facility than their sisters fixed on the rocks; for they do not have to wait, as the others must, until food drifts casually to their tentacles.