Like Kairuku and Dimetrodons, Otters can provide insulation based on their damage status. They are, however, easier to tame and can be carried on shoulder opposed to Dimetrodons, with a smaller hitbox than both the other two while retaining a good insulation capacity, so it's possibly to easily gather as many as 12 around a single egg.
On the con side, their insulation AoE is quite small, so hatching multiple eggs might require a ton of them, wasting creature slots. They have a very low Food stat as well, moreover they are mammals and thus cannot have their genetics stored in the form of eggs inside fridges, so stay ready to feed them fish every 4-5 days.
Otters also act like structure storage units, so one can use them to carry as many Artifacts as it wants.
Level up Melee Damage for portable ACs and living scarfs, Weight for Artifact backpacks and Food as a security measure on breeding stock.
I once had an otter that I named harry otter , he was a great otter he got me all the silica and black pearls I needed, he once saved me from a megalodon , he kept me warm to, he was a great companion I took him almost everywhere,but one day I was farming pearls with him I threw him at a fish to get pearls from it but instead he disappeared I looked and looked for him only to not find him but uneven got a message that he was dead, he's still out there somewhere, I still look for him to this day. #prayforharryotter