The Egg Fort II is a flying fortress used by Dr. Eggman in the first season of Sonic X.
It was actually made out of three ship components, controlled by Eggman, Decoe and Bocoe (these components were named 1, 2, and 3 in the English version):
Bang, controlled by Eggman himself and the most powerful of the three.
Babang, controlled by Decoe.
Bababang, controlled by Bocoe.
It was first used as Eggman's second base in "Cruise Blues" after the Egg Fort failed. In the episode 26 "Countdown to Chaos," Eggman transformed the Egg Fort II into the E-99 Eggsterminator, powered by the Chaos Emeralds. However, Chris took the emeralds and they fell into the sea, where they were absorbed by Sonic and transformed into Super Sonic, destroying the Eggsterminator.