Basking Sharks & Shrimps
Just an idea me and a couple of others had for a fun ambient mob to roam the seas. Basking Sharks, Shrimp, and an interaction between the two
Basking sharks - non-aggressive sharks in real life meaning they would not contradict Mojang's rule on sharks. These basking sharks are also endangered so bringing attention to them would be nice. They would add more to warm oceans (spawning in them), being a peaceful mob with no drops. They'd be ambient and just swim around. Sometimes they would open their mouths a bit just as a fun idle animation. They also have another animation where they’ll occasionally rise to the ocean surface and jump up a few blocks before falling down again. No real reason, it’s just a thing they do in real life to get rid of parasites and would be pretty cool to see around the world :)
Shrimps - very small mobs, possibly like fireflies. They spawn in a group. They could be right clicked to pick up and eat similarly to berries. They also drop on death. If this would be too easy of a food source, you'd have to mix them and dried kelp in a crafting bench to make a new food source.
Interaction - basking sharks swim towards a shrimp group with their mouth wide open and eat them.
After seeing the Wild Update and how it adds to the overworld, I think it would be a great opportunity to bring attention to this species that certainly needs it, along with adding a new food source it can interact with.