Throw block

From SMWiki

Throw blocks look like blueish Turn blocks. Mario can pick up these blocks to activate them. Then he can carry, put down, and throw these blocks to complete a variety of tasks. Throw blocks kill most enemies on contact, and can take out a whole line of opponents. They can also be used to hit other blocks to activate their effects from a distance. Throw blocks will shatter upon contact with a select few sprites and most solid objects, and if they're active for too long. With precise timing, you can even spin jump off of an active Throw block!