They're these little babies that hatch from eggs. They can do many things, and are very picky about what they play with because they're stupid (J/K about the last one) :).
An extremly rare and valuable Yoshi!
"Who want''''s to buy a gold Yoshi? Selling Price, $99,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999!" (almost 10 Googols!)