Sea grapes

Sea grapes (ウミブドウ, Umibudō) are deep sea creatures found in.

In New Leaf
Upon donating the sea grapes 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 deep sea creatures. It is found in the corner of the pool nearest to the entrance. The exhibit has this to say about the sea grapes:

"Sea grapes are small spheres attached to slender stems on branches, similar to normal grapes. However, despite looking like and being called "grapes," they aren't much like the land-based variety. They grow in warm oceans and are very susceptible to cold conditions, meaning refrigeration is difficult."