Based on crayfishes, Yagos have torpedo-shaped bodies. They have small black eyes with an orange head section, black rims around their eyes and a small gray jaw each. Their lower bodies are heavily armored with a pair of orange claw-arms covered in armor too, and a black rear which has a gray turbine for propulsion attached. Decayed Yagos show an alternate color scheme, having yellow-green and blue armor instead of orange and gray.
In Sonic the Hedgehog CD, Yagos appear as enemies in the water sections of Tidal Tempest. In gameplay, they swim along the sea floor very slowly within their designated area. When the playable character gets within their range and they can see them though, the Yagos will suddenly lunge toward in the direction that the playable character is standing in an attempt to ram them. However, the player can easily dodge this attack by jumping or by destroying them with a Spin Attack.
In the Bad Future or sometimes the present timeframe of the Round, the dilapidated Yagos have an arched body and broken armor on their bodies, arms and rear. While they maintain their previous attack patterns, they move slower when attacking and can only hop. Also, like every Badnik in the game, they are powered by Little Planet flower seeds which will pop out of them when they are defeated.
- "Yago" (ヤゴ?) is the Japanese word for "dragonfly larva".