A Spiny Egg (also called a Spiny's Egg) is the state of a Spiny before landing on the ground. They are commonly thrown by Lakitus and other foes. They tend to bounce on the ground before emerging into Spinies. A Spiny Egg can be destroyed before it hatches by tossing a fireball at it or having Yoshi swallow it. They can also be frozen with Iceballs.
Spiny Eggs are seen Super Mario World. They are commonly thrown down by Lakitus as their main weapon, a Spiny Egg can be destroyed with a Fire Flower or a Starman. Yoshi can also destroy them by swallowing them.
Spiny Eggs are tossed down by Lakitus in Super Mario World 2: Yoshi's Island. They aren't thrown in the same frequency as in other games and the Lakitus also take aim before firing, additionally, the Spiny Eggs don't become Spinies upon hitting the ground, instead they merely explode. Spiny Eggs can be defeated by being swallowed or by tossing an Egg at them. Wall Lakitus and Aqua Lakitus also toss Spiny Eggs as well.
Spiny Eggs are back in Yoshi's Island DS. In this game, they function identically to how they did in the previous game and the way to destroy them is the same. They can be seen in the Museum being tossed down by Lakitus and Wall Lakitus. Once again, they don't turn into Spinies upon hitting the ground.
Spiny Eggs are once again used as a Lakitu's primary weapon in New Super Mario Bros. Wii. In this game, they are commonly tossed down by the Lakitus in the traditional sense becoming Spinies upon landing, they can be destroyed with the effects of a Fire Flower, Shell, or a Starman. They can also be frozen with the effects of the Ice Flower. Additionally, some Lakitus toss Coins down instead of Spiny Eggs.
In Super Mario Galaxy 2, Lakitus once again toss Spiny Eggs which become Spinies however, due to the new 3D environment, their range is now expanded and they now longer merely dunk them down. They can be destroyed with a Rainbow Star. Yoshi can also swallow a Spiny (or a Spiny Egg) and upon spitting it out, it will become a Spiny Egg as it is launched. Using this method can also defeat other enemies and break open objets that are otherwise unbreakable. Giga Lakitu also uses Spiny Eggs as his primary weapon and has much larger range.
Spiny Eggs return in New Super Mario Bros. U as Lakitu's main weapon. They once agin become Spinies upon landing and the way to destroy them is the same as before (with the Fire Flower, Shells, or a Starman). They are dunked in the same way as before. A new variation of the Spiny Egg also appears in this game called the Piranha Plant Egg, these become Piranha Plants upon lading on the ground.