Coat appears to be of finished Mahogany, various parts replaced with brass clockwork. Mane and tail have been replaced with segmented brass. He was once an earth pony but clockwork wings were built on to him.
A bigger image for detail.
A working clock
He is good with clockwork and antiques. He can make even the oldest of items work with some tinkering, though newer technology is hard for him.
Time Clock was taken as a young colt, not long after he received his cutie mark, a clock. Where he was taken he was not sure, but he would describe it as a nightmare of steam, pistons, gears, and brass, embedded in polished wood eternally running an unknown machanism. The "pony"
who took him there decided Time Clock would be much better off if he were made of clockwork. So began a slow transformation from a normal earth pony to a clockwork Pegasus pony. Eventually his cutie mark was replaced with a working clock and he was given the frame work for clockwork wings, allowing for limited flight. Before he was "finished"
Time Clock escaped. He ended up in Bridle shores where he found a job in antique repairs and maintaining the clock tower.
Time Clock is friendly, but often seems to be on edge. He is most comfortable in the clock tower, or when working on some sort of antique. He avoids drawing attention to himself, not because he is shy, but because he is nervous that his old captor might notice him.
He is new to the community and tries to draw little attention to himself, though he is always willing to help when needed. Though his shop "Back In Time: Antique Sale and Repair" is now open so that could change.