An elaborate tapestry, if removed from the wall, reveals hundreds of ice needles that shoot from the wall for 1d6 piercing damage, plus 1d4 cold damage.
The needles take 1 minute to melt, during which time they impose a further 2d6 cold damage. If the needles are removed manually, they deal 3d6 electricity damage and stunning (for 3 rounds) anyone touching them.
Snowflake by Aaron Burden, modified by Seth in GIMP on Fedora Linux. Unsplash License.