Each of the three Silent Ones were roughly eighty feet in length, with heads similar to that of a snake yet sporting fish-like faces. They had fat bodies, tentacles in place of arms, and massively thick legs akin to those of an iguana. Although they were stated to possess gills, they seemed to be capable of comfortably surviving on land, at least for a short period of time.
The three Silent Ones slept in an ancient ruined temple (said to be reminiscent of a gladiatorial arena) within the aquatic Deep One city of Y'ha-nthlei just off Innsmouth harbour. The one known as G'hlaballa had its body inhabited by the ghost of a man known as John Masters who used it to kill the Deep One Toadface before heading back to the ocean to feed on whales.
The origins of the Silent Ones, how long they had lain dormant in their temple, or indeed how they even came to rest there, remains a mystery, although it is possible that they may have been either gods of the Deep Ones or Great Old Ones, as Toadface stated that by possessing G'hlaballa's slumbering form, Masters was committing an act of blasphemy.