This brown cloak seems to be composed entirely of long thorns.

A cloak of thorns grants you a +2 enhancement bonus to your existing natural armor bonus. (A creature without natural armor has an effective natural armor bonus of +0.)
In addition, any creature striking you in melee with a natural weapon or nonreach manufactured weapon takes 1d4+3 points of piercing damage.

Prerequisites: Craft Wondrous Item, barkskin, command plants.
Cost to Create: 13,000 gp, 1040 XP, 26 days.