Was very interesting learning about the animals that are still with us on the planet that have ancestors in the fossil records that stretch back to the origins of life 3.5 thousand, million years ago. I would say billion but for the fact a billion is actually a million times a million, the Americans love to shorten everything!
The reasons this is fascinating is because there are significant changes, not just Ice Ages but the meteorite they know killed off the large dinosaurs and the flows of lava that lasted millions of years that made seas toxic yet these animals still survived: because their habitat was not drastically affected living on the margins and in the depths, because the were generalist feeders, because they were able to deal with toxins, because they were suitably armoured and able to survive horrific injury. It was also interesting that three such animals live in and around Hong Kong’s waters, which says something about how unaffected by the extinction events those seas have been.
We can add another adaptation to these which is the use of intellect which is also highly adaptable but in the realms of the unexpected large animals like us do not fair well. And the extinctions we are now responsible for will still leave these smaller animals living on waiting, one may suppose, for one of those chance episodes which leaves them once again, the only survivors.