Great little chest, I like how it bounces when opening and closing :D
(Now, add some teeth and make it jump around, and you'll have a neat little mimic :D :D )
The colors are nice, smooth. The chest could stay opened longer (possibly just as long as it stays closed) so that we could see it well.
Still, it's a great animation.
Do you know the Dwarf Fortress tileset called SpaceFox? This one kind of reminds me the style of that tileset. Nice work and style!