The 250m (600ft) design, which turned up in a field near Ashbury last week, is believed to be the first of its kind in the world.
Crop circle expert Karen Alexander said: "We have seen butterfly and bird patterns in the past, but this is the first jellyfish crop circle in the world.
It is absolutely huge - roughly three times the size of most crop patterns and extremely interesting. People have been aghast at the size of it. It is a complete monster.
The owners of the land say whoever created the design caused about £600 of damage - but they called the shape "beautiful" and say they have reported the trespassers to the police.
