Are spells that do only bludgeoning, piercing, or slashing damage considered magical or nonmagical damage? Most especially when considering them for purposes of resistance/immunity against "bludgeoning, piercing, and slashing from nonmagical weapons that aren't silvered".
For example, Thorn Whip I can see two sides:
It is being created by a spell, using a melee spell attack to hit, and the spell damage increases with level. Thus it is magical damage.
The spell description only states piercing damage, and it's the object created by the spell that does the damage rather than the spell directly. Thus it is nonmagical damage.
Similar arguments can be made for other spells (such as Earth Tremor), or portions of other spells (such as the piercing damage of Ice Knife). I'm interested in the rule(s) for this class of spell damage, rather than the specific spells.
[1]: Thorn Whip spell can be found in the Player's Handbook.
[2]: Earth Tremor, and Ice Knife are spells found the Elemental Evil Player's Companion.