Chambered nautilus

The Chambered Nautilus (オウムガイ, Ōmugai) is a type of sea creature introduced in.

In
Upon donating a Chambered Nautilus to the museum, it can be found in the small tank on the left hand side in the first room of the sea exhibit. The exhibit has this to say about the Chambered Nautilus:

"These creatures are related to both octopi[sic] and squids and originated about 60 million years ago. They have air and body fluid in their shells and move by adjusting the amount of body fluid inside. This allows them to either float or sink depending on the situation they find themselves in. They have nearly 90 tentacles that stick out from under their shells to grab on to rocks or prey."

In
When donating to the museum, Blathers will say the following:

"The chambered nautilus is perhaps best known for its gorgeous shell. Not only does this shell's interior shine with a pearly luster, it features a near-perfect natural spiral. But those aren't the chambered nautilus's only bragging rights. This cephalopod can have up to 90 tentacles, it's said! These arms come coated with a sticky substance that helps the nautilus capture its prey... Which is far better than using then for overly long hugs, I say."