If you haven't seen this video, you need to watch this. A young woman innocently is walking about amongst tidal pools, sees some crabs, goes in for a closer look with her camera - and then something happens. Something awesome.
Incidentally, see if you can spot three crabs in this short but exciting video. Yes, there are three - look closely. The are scattered far apart.
An amazing capture of something that, well, you don't see every day! And look closely in the water by the crab right before the climax, you'll see death approaching craftily and silently.