get_overlapping_areas() detects other Area2Ds.
get_overlapping_bodies() detects PhysicsBody2D types (RigidBody2D, KinematicBody2D, or StaticBody2D).
Note that as stated in the Area2D documentation, the
get_overlapping_* methods are only updated once per physics frame. It is typically preferable to use the area's
This would be perfect for your situation. Mario entering the "Thwomp Scan Area" will trigger the
body_entered signal and you can make the Thwomp fall.