Martian Probe

The Martian Probe is a rare Hardmode, post-Plantera flying enemy that can spawn anywhere on the surface after the Golem boss is defeated. It flies through blocks. The Martian Probe initiates the Martian Madness event if it detects a player and is then allowed to escape off-screen.

A Martian Probe flies around, attempting to detect players; if successful, it turns red and attempts to fly away. Destroying the Probe prevents the event from occurring, but if it escapes, the Martian Madness event begins immediately.