The Destroyer

The Destroyer is a hardmode version of Eater of Worlds boss, which was introduced in the 1.1 patch.

The Destroyer has a metallic-like body unlike Eater of Worlds which has a corrupted worm body. The Destroyer has red lights in its body. Those lights are Probes that The Destroyer sends out. If the light isn't lit up, that means Probe was already launched from that segment. Left over parts of Probes are able to return to empty segments and possibly restore. (not confirmed)

It is summoned using a Mechanical Worm.