Piranha Plorps are Piranha Plant-like organisms located inside Bowser's body in Mario & Luigi: Bowser's Inside Story. They have a vein as a stalk unlike the other Piranha Plants with a vine with leaves on as a stalk. They can be found in the Energy Hold.
Their attacks are spitting poison at Mario, or fogging up the entire screen and spitting a red or a green blob at Mario or Luigi depending on the corresponding Bro. This attack be avoided with the hammer. Another one of Piranha Plorp's attacks is spitting poison back and forth on which Mario and Luigi must avoid by jumping over the poison all at once or else they have a high chance of getting the status poison. They are weak to fire so Mario and Luigi can use Fire Flowers to cause a good amount of damage to them.