Use a Tropical Wiggler on the roots of the nearby trees in the poison water to reach it! (mariopartylegacy.com)
At the Swamp Hill checkpoint, possess one of the Tropical Wigglers on this raised platform and use their stretch ability to reach over and grab the four coins floating above the purople gloop. (eurogamer.net)
It has a lap strap to keep little wigglers in place and it is easy to clean, even though you can not take it apart. (babycomfortauthority.com)