Queen Myxine and her changelings. They live in hollowed out caves along the shore and eat seafood to produce their building material (which might resemble corals). Usually they’ll either play the drowning to be saved, or save the drowning. Sometimes they build sharp spires underwater and try to navigate ships into them. Sometimes they’re lazy and just simulate a shark attack by swimming with their horn looking up over the water like a shark fin.
They are a pretty small hive as ponies aren't all that big on seafaring. Overall they’re pretty pragmatic and a direct contrast to the Honeycomb hive’s song and dance.