Put the summary of the bug you're having here
I made a creeper face with clay.
What I expected to happen was the ender Dragon would respawn and the crystals to reappear.
What actually happened was...:
The ender Dragon spawned, but no Crystals
Steps to Reproduce:
1. Open 15w33b
2. ...go to the end
3. ... make creeper face with clay.
Environment
Windows 8
This is a missing feature, not a bug. Mojang has yet to introduce a craftable ender crystal that respawns the dragon in the snapshots. When they make a permanent and finished way to respawn the dragon, you can bet that the ender crystals will respawn.