One of my photos depicting a social unit of sperm whales (Physeter macrocephalus) appeared as Bing Wallpaper of the day in the US:
The large individual in the foreground is the matriarch. The trio in the middle were juveniles at the time. It took a long time for the whales to warm up to me, but eventually the young ones' curiosity got the best of them. One swam over, mouth agape, biosonar pinging. I passed inspection and became a playmate.
Good times.
Note the bone structure in the pectoral fin of the matriarch. Those are analogous to the bones in our hands. Different, but the same.