|Introduced in||"Ricardio the Heart Guy"|
Plantoids are a type of microscopic organism. They are mentioned in "Ricardio the Heart Guy," when Ricardio discusses them with Princess Bubblegum. Princess Bubblegum remarks later in the episode that Ricardio's understanding of Plantoids is "pretty weak."
They secrete deadly mallotoxins which kill off Zanoits. Even so, hundreds of thousands of them are killed by Zanoits every year.