[B]iologist Roland Anderson … helped to design an experiment for a female giant Pacific octopus … named Billye. … A fellow female octopus named Pandora had gotten tasty hunks of herring in a screw-top jar, which over several tests took her an average of two minutes to open. Anderson … decided to … ‘offer [their captive octopuses] childproof pill bottles.’ … Anderson and his team at the aquarium had drilled small holes in the plastic bottle so Billye would be able to get a whiff of the meat inside. Fueled with this incentive, she managed to open the bottle … in … about fifty-five minutes. … With a little practice, she was able to get it down to an average of about five minutes.
It was the kind of child-proof bottle where you have to push the lid down while turning it. I just got one of those from the pharmacy. After I open one of those I won’t tighten the lid again. My mother often had me open her childproof bottles. There have been times I’ve been tempted to saw the top off.
source: Octopus! the most mysterious creature in the sea by Katherine Harmon Courage