|Reality World||Mirror World||Space Eagle||Past Versions|
|- !3-star Score |: 126,000 points |- |- style="text-align:center" | Previous | Next |- style="text-align:center" | Cosmic Crystals 7-20 | Cosmic Crystals 7-22 |} Cosmic Crystals 7-21 is the twenty-first level in Cosmic Crystals. The objective of level 7-21 is to use the birds to eliminate all the pigs. Get at least 126,000 points for 3 stars.
This level is very hard because:
- timing is everything in this level. It's hard to send the birds correct time.
- Getting three stars is very hard.
Send Terence to destroy the southern planet. Release Terence when the orbiting TNT is approximately at the 9 o’clock position due west relative to the planet. The TNT will drift to the main structure, blasting it to smithereens. Even if all pigs are popped, it’s worthwhile to send another Terence into a large pile of debris.