Sad Dry Bones
From the Super Mario Wiki
Sad Dry Bones is like a regular Dry Bones, but with a blue coloration. Once it falls apart, it will re-assemble itself. The Sad Dry Bones will throw bones like its regular counterpart, except that it throws three bones at a time instead of one. It cannot be picked up with the .
According to the game's Glossary, it "Weeps sadly and throws bones."