by Martha Wells
These beings are advanced in the arts of warfare, and in their countless millions it would be an easy matter for them to overwhelm the surface of the world, conquer and enslave our race, or if they wished, destroy it utterly. However, they do not covet the dry land, and prefer to trade and breed with us in secret, as it suits their needs.
There is a sign inscribed on certain small stones that the Deep Ones respect in a religious way and will not cross over. Those islanders who wish to terminate their trade and intermarriage with the Deep Ones scatter these stones along their beaches to express aversion. In doing so they risk a terrible wrath, for the Deep Ones do not like to be spurned and will exact vengeance when the chance presents itself. No vessel, large or small, may pass across the waves without their sufferance.
It may be that the signs engraved upon these small stones are linked to an enormous white obelisk carved all over its surface with alien letters and signs that resemble sea creatures. This obelisk great Dagon himself is said to cherish and adore deep beneath the sea, but of its origin, whether on this world or a world among the distant stars, nothing is known.