Living in a post-flood world the group I miss the most are the echindoderms. The starfish, sea urchins, sand dollars, sea cucumbers, and, most of all, the sea lillies (crinoids). Because this group all have a water vascular system and no means of ionic control they were all destroyed during the Great Flood. Because even a slight change in ionic balance (40 days of rain or fountains of the deep) causes them to explode internally. This is why this group, however diverse, never evolved freshwater forms in their 600 million year history. Oops, I mean 6000 year history.
Wanda: To call you stupid would be an insult to stupid people. I've known sheep who could outwit you. I've worn dresses with higher IQs, but you think you're an intellectual, don't you, ape?
Otto: Apes don't read philosophy.
Wanda: Yes they do, Otto, they just don't understand it.
"A Fish Called Wanda"