Acorn barnacle

Acorn Barnacles (フジツボ, Fuji tsubo) are a type of sea creature introduced in.

In
Upon donating an Acorn Barnacle to the Museum, it can be found in the large pool in the first room of the Ocean exhibit, along with many other species of sea creatures. It is found on the large rock. The exhibit has this to say about the Acorn Barnacle:

"They attach to hard places, and though they look like bivalves, they are related to shrimp and crab. Some species are even edible and have a very crab-like taste to them, making them a fine delicacy. Young acorn barnacles come from eggs, do not have shells, and float around the ocean like shrimp. They gradually develop their shells as they grow into the image we usually see."

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

"Do not mistake the acorn barnacle for a relative of the clam. Tut-tut, mollusks they are not. Barnacles are cousins to crabs and lobsters, you see. Though the family resemblance is hard to spot. Acorn barnacles may also seem to live a stationary life, what with being attached to rocks and such. But truth be told, baby barnacles are avid travelers, drifting shell-less about the sea before settling down. Once they find a good rock to affix themselves to, they float free no more. Which begs the question... Do adult acorn barnacles ever look out across the open sea...and long for youthful adventure once more?"