Answer:
It can be, but it isn't always so.

Adverb: It spiraled downward. The verb is modified by 'downward'.
Adjective: It moved in a downward spiral. The noun 'spiral' is being modified here.
Contributor: Bryan
First answer by Bryan Shepard. Last edit by Bryan Shepard. Contributor trust: 114 [recommend contributor recommended]. Question popularity: 0 [recommend question].