The Giant Polyp is a sapient aquatic entity who resides in a small lake on Shalmirane and is one of the last followers of the Master, an ancient Human prophet. The species to which the Polyp belongs is yet unnamed.
An intelligent but rather unusual being, the Polyp is actually a colony of millions of tiny cnidarianoid organisms and always refers to itself in the first person plural. Being essentially a superorganism, the Polyp can change its shape, creating or retracting tentacles and articulated limbs.
The Polyp has three eyes arranged in the shape of an equilateral triangle, at the center of which there is a semi-transparent membrane. It can vibrate the membrane to create sounds in any frequency range, which enables it to communicate with many different species. The Polyp controls the frequency of its vocalizations by changing the size of its membrane.
Other organs include a frill of short, delicate palps that constantly agitate the water, ventilation openings that open and close, and multiple short legs used for walking on land. All of these organs, along with the tentacles, eyes and membrane, are usually retracted into the creature's body when not in use.
The Polyp is essentially immortal. At long intervals, the millions of tiny creatures that make up its body separate from each other, disintegrating the Polyp. It then ceases to exist as a single, conscient entity to become millions of non-sapient stinging organisms that reproduce by binary fission. Many years later, moved by unknown forces, the cells unite once again and the Polyp is reborn, somehow retaining all memories from its previous intelligent phases. This unique lifestyle renders the Polyp virtually immortal as an individual.
The Polyp, along with its robot companion, is the last follower of a religious cult dating back to more than a billion years ago, in the time when Humans, Polyps and innumerable other species were all members of a powerful and technologically advanced Galactic Empire. The Master, a wise Human prophet born in the artificial star system of the Seven Suns, funded the most successful religion of history, attracting followers of many different races.
When the Empire started collapsing, the Master, his robot and his most loyal followers came to Earth. Among them was the Polyp, who traveled in a seawater-filled spaceship. Before the death of the Master, the members of the Galactic Empire abandoned the galaxy, and possibly even the material universe, by unknown means, leaving the galaxy mostly devoid of living civilizations. Shortly before his death, the Master told his followers to wait for their return (the "return of the Great Ones") and receive them when it happens.
Through the eras, the history of the galaxy was lost and the galaxy lost knowledge of who the "Great Ones" were. The Master's religion started decaying and the followers diminished in number until the only remaining ones were the Master's robot and the Giant Polyp. They two reside in a small lake on Shalmirane, an ancient artificial crater with a powerful weapon which was used to destroy Luna, the moon of Earth, when it was going to collide with Earth. They still believe in the return of the Great Ones and periodically send stunningly bright light messages to the skies to see if they receive any answer. Such messages are sent using a powerful reflective device.
- The City and the Stars, by Arthur C. Clarke