Nipper Spore

Nipper Spores are obstacles that spawn Nipper Plants, commonly seen in the Yoshi franchise. Generally, they resemble red spheres that are attached to white balls of fluff via small, black or yellow stems.

Yoshi franchise
Nipper Spores (along with Nipper Plants) are traditionally introduced in the first underground level of Yoshi platform games.

Super Mario World 2: Yoshi's Island / Yoshi's Island: Super Mario Advance 3
In Super Mario World 2: Yoshi's Island and its enhanced port, Nipper Spores are first encountered in The Cave Of Chomp Rock. They descend slowly from a certain height to the ground. Simply touching one will cause Yoshi to drop Baby Mario off his back. Upon coming into contact with the ground, they transform into a Nipper Plant, which starts walking right away. Yoshi will swallow a Nipper Spore directly upon eating it, without producing an egg.

Yoshi's Island DS
In Yoshi's Island DS, Nipper Spores first appear in the level Ba-dum BUM!. Throughout the game, some Nipper Spores are produced by Nipper Dandelions. When strong gusts of wind blow (usually caused by Windbags), the Nipper Spores are blown off of the Nipper Dandelion and into the air, until they land and become Nipper Plants.

Yoshi's New Island
Nipper Spores return in Yoshi's New Island, acting the same way as before. They are first encountered in the level Cave of the Nipper Plants.

Yoshi's Story
In Yoshi's Story, Nipper Spores have spikes on them. They are also foul tasting, meaning that they will hurt any Yoshi (except for the Black and White Yoshi) that attempts to eat them.

Yoshi's Woolly World / Poochy & Yoshi's Woolly World
In Yoshi's Woolly World and Poochy & Yoshi's Woolly World, Nipper Spores are first present in the level Sponge Cave Spelunking, where they act the same as in the Yoshi's Island series. Nipper Spore Patches are sometimes encountered in large blocks of wool that can be unwoven; they behave identically to a regular Nipper Spore.

Mario & Luigi: Dream Team
Nipper Spores also appear in Mario & Luigi: Dream Team, where Piranha Plants in battle spit them out into the background to create Fiery Walking Piranhas.

Super Smash Bros. Ultimate
In Super Smash Bros. Ultimate, Nipper Spores are mentioned briefly by Viridi during Palutena's Guidance dialogue for Piranha Plant. Unlike most other variations generally mentioned in order of appearance, they are listed amongst Super Mario Bros. 3 debuts. Big Piranhas, Big Fire Piranhas, Small Piranhas, and Fire Stalking Piranhas are similarly listed out of order.