Dragon Turtle Shell spell and Unarmed Strikes

[Barachiel Shina]

Does this spell work on Unarmed Strikes? Since unarmed strikes count as natural weapons or do they count as manufactured? I believe for Monk it can count as both, whatever is more beneficial.

[Derklord]

"Unarmed strikes do not count as natural weapons" CRB pg. 149

Unarmed Strike counts as neither a natural nor manufactured weapon. That's true for a Monk's, to - their US is treated as both "for the purpose of spells and effects that enhance or improve", but not for negative effects, nor for general rules.