Cephalopods include octopuses and squid, and are common throughout the Ecco universe. Most simply impede Ecco by swimming at him or blocking his path, but some swim freely like Orthocones.
Orthocones are found in the prehistoric levels of Ecco the Dolphin. They also appear in Ecco Junior. A smaller variety appears in The Lagoon of Stonefish in Ecco Junior. Slender Orthocones are the more durable horizontal-swimming variety.
Eight Arms is an obstacle enemy found in Ecco the Dolphin. It cannot be defeated and must be swam past, albeit slowly. The Gate Keeper is the Ecco: Defender of the Future equivalent.
The Green Octopus is a creature found in the Octopus Passage and Aqua Maze in Ecco Junior. It cannot harm dolphins but it sits near the passage's exit.