The Egg Lobster was an attack vehicle developed by the Eggman Empire.
The Egg Lobster moved on the ground with its legs. It could fire lasers from its tail and grab and sqweze enimies in its claws. 
Snively used the Egg Lobster to get revenge for Shadow takcing his last remaining scalp hairs. Knuckles fought off the Lobster while Shadow learned about his past from Gerald's diary. Shadow destroyed the Egg Lobster upon his return.