Minecraft wiki entry for Weird_Piston, associated text: Multiple block transmutation methods can be used to create weird pistons in Java Edition.From Beta 1.7.2 to Beta 1.9 Prerelease 5, weird pistons can be created using moving piston merge transmutation, from Beta 1.7.3 to 1.2.3, can be created using water transmutation, and from 13w36a-1 to 1.7.5 and 14w02a to 14w11b, can be created using arrow transmutation.