From the Super Mario Wiki
Seedy Pods are a blue variety of Pokey Sprout with yellow flowers and blue skin. They only appear in Bianco Hills and a minicourse during the events of Super Mario Sunshine. When approached, a Seedy Pod burrows underground while launching its seeds at would-be attackers. The creature can be defeated by stunning it with water from a safe distance, and then jumping on top of it. Once defeated, the Seedy Pod drops a Coin (or a Red Coin when in the Red Coin Field). Seedy Pods can be heard singing and seen dancing when one is standing far away. Musical notes even appear above their heads while singing. A Seedy Pod can be eaten by Yoshi when it's in its invincible state.