From the Super Mario Wiki
Gūrindai (グーリンダイ) are an alternative to Spiny Eggs for Lakitus to throw. They appear only in New Super Mario Bros. U and New Super Luigi U, being featured in the level Blooming Lakitus. They grow into Piranha Plants upon landing.
"Gūrindai" is derived from yet another part of the folktale character Jugemu's name.