Breeding zombies

[rdebath]

Place one zombie block, drop a sand block on top of it. Multiple zombies spawn. Also works for creeper blocks.

[UnknownShadow200]

Is there a specific pattern that must be used?

I think I am missing a step, I was unsuccessful in reproducing at physics level 4 and even with physics slowed down to /ps 5000

[rdebath]

Why don't those zombies have heads?

I think the Zombies/creepers do have to be in motion; I set myself flying above them then /pl sand to drop a block on top.

The Zombie it lands on then seems to stay in the same position with new ones appearing around it.

/client turn on noclip
/newlvl test 128 64 128 flat
/g test
/physics 2
/pl zombie ~ 33 ~
/pl sand

May need to remove the sand and try again two or three times if it doesn't end up at (64,35,64).

/ms zombie
/ma

This gave 200 zombies and climbing a little while later.