Black Swallowtail Chrysalis. Before forming this harder outer skin the caterpillar spins a safety line (top left) to hold it in place. They then shed off their outer layer of skin which you can still see here (middle right) somewhat still attached. Their skin then goes into a transformation taking on a wood-like texture to mimic a plant stem.
Black Swallowtails overwinter in the chrysalis stage and its around this time of the year that it becomes uncertain which chrysalises will hatch in a few days and which will wait until 6 to 8 months and hatch next spring.