Just three months ago a paper was published reporting the first observed case in the wild of tool use in fish. Now, a different technique has been observed being applied by the same species but a different country. And this time they have video.
Presumably tuskfish have been doing this for millions of years, and the coincidental discoveries are a combination of the increasing number of scuba divers and blind luck. But it is fun to imagine the fish have actually been watching human swimmers, and have only just picked up a few tricks.