I know a lot of this info has already been said, but this is a full recap of it’s features:

Insulation - Yep, having it on your shoulder protects you from temperature, but mostly cold. Both of these scale with the otter’s attack, but their percentages are different. Cold gets roughy 70%-75% of the otter’s attack, while heat only benefits from around 25%. This is still useful for hot environments, but don’t count on the otter to guarantee remove all the heat from you, it’s more suited for the cold environments.

Egg Hatching - Their insulation also counts towards eggs, giving the same benefits if you have them next to the eggs. No need for an air conditioner, just get 2-4 of the otters, level their attack, and sit them next to your eggs.

Fishing/Pearl Farming - This was probably my biggest issue with the otters. They farm fish for black and silica pearls, but the AI of the otter is weird. There’s a few ways to get the otter to dive down for the fish, though it can still be pretty inconsistent. The solution I’ve found that work best for me is to have the otter on your shoulder, and swim to the fish. Have the otter set to attack your target, and just punch the fish once.

Note: DO NOT KILL THE FISH, the otter must do the finishing blow to get you pearls, punching the fish just lets you target it with your shoulder buddy