A tiny, greenish-black juvenile Leaf scorpionfish (Taenianotus triacanthus), approx 2 cm long.

This is unquestionably the smallest juvenile Devil scorpionfish (Scorpaenopsis diabolus) I've ever seen...as you can tell from the sand grains in the foreground, this little one is about 1.5 cm long. Thanks to diver Jennifer Cotton for spotting this one for me!