From the Super Mario Wiki
Bungee Piranhas, or Bungee Piranha Plants, are purple Piranha Plants that use their stem as a bungee cord. They only appear in Yoshi's Island DS. Bungee Piranha Plants are very similar to Elasto-Piranhas. They hang on ceilings, waiting for prey (which is usually a Yoshi) to come along. They then bungee down, attempting to grab their prey. A bigger and boss version called the Big Bungee Piranha appears in World 2's Castle, Big Bungee Piranha's Lair. They appear in The Cave That Never Ends, Let There Be Light!, Yoshi on Stilts, Yikes! Boiling Hot!, Big Bungee Piranha's Lair, Moving Statues, Standing Statues, and Superhard Acrobatics.