Thick carapace armor grows around a creature you touch, becoming a protective second skin. It lasts for the duration. This carapace armor requires no proficiency and has no strength requirement. It weighs nothing, and counts as light armor. A creature with the carapace also gains resistance to non-magical bludgeoning damage. 

While not wearing armor, a creature wearing the carapace's AC becomes 14 + their dexterity modifier. They can still choose to do this is a creature with the carapace is wearing armor, but has less AC than when using the natural armor. A shield’s benefits apply as normal while a creature uses this natural armor.

A creature wearing armor can instead gain a +2 bonus to their armor class.

At Higher Levels. When you cast this spell using a spell slot of 4th level, the duration becomes concentration, up to 24 hours. If you cast this spell using a spell slot of 5th level, it does not require concentration. If you cast this spell using a spell slot of 9th level, it becomes until dispelled.