Special Blue Watermelon
From the Super Mario Wiki
Special Blue Watermelons are blue Watermelons found in Super Mario World 2: Yoshi's Island and its remake Yoshi's Island: Super Mario Advance 3. They may be cold, but it is uncertain. If a Yoshi eats it, the dinosaur will be able to breathe three blasts of ice. The ice can freeze enemies solid, which can then be smashed to pieces.