Crown is a period-12 oscillator that was found by Noam Elkies on January 3, 1995. Alternatively, it may refer just to the 10-cell piece at the top of the oscillator in generation 10 (shown below in green) that is hassled by two caterers and a heavyweight emulator.
It is used in the pi orbital and p156 Hans Leo hassler.
52-glider syntheses are known for two variants of this oscillator, one in which the caterers are oriented differently and another in which they are replaced with two jams.
By replacing the caterers with extensible p3 oscillator, an extensible crown can be made:
Generation 10 reveals a piece that by itself is sometimes referred to as the crown