Haven't had too many of those.. I'm not rattled Too easily I guess. But around my 40th dive or so had gone crab hunting for dungenness crab under an oil dock with someone I had just met. It was our second dive together, and he supposedly had done this dive many times. It was my first time crabbing.
Vis was pretty bad, maybe a couple meters and crabs kept popping up out of the sand and kicking silt up. He spotted a crab and took off and disappeared. I proceeded to try to figure out the best way to locate him and found him after a 5-10 minute search. He had the crab net so I wanted to find him to give him my crab which was the point of the dive.
5 minutes later though he did it again! I had two large and possibly angry crabs in my hands, no net, and no buddy. I poked around for a while to find him or find a bigger crab but it got EXTREMELY creepy under the oil dock. It was super dark. Crabs are basically like monster cockroaches that breathe underwater and have claws, and my octo hose kept brushing my arm and freaking me out.
That was the moment. I suddenly realized this wasn't a bright idea and being under a dock (most of the dive was not directly under it) im technically in an overhead environment with no buddy and if something went sideways I might actually die while clutching these two crustaceans LOL. The hose touching my arm wasn't helping.
Navigated back to about where we started and surfaced surprisingly next to some other diver who lost his buddy. Then noticed my "buddy" pop up 40 meters or so away with a bunch of crab and not particularly worried about finding me!