A United States F-15 pilot, who was downed in April, reported seeing an Iranian drone swarm in the shape of a “jellyfish” before ejecting from his aircraft, four sources familiar with the matter have told CNN.

“Multiple drones interconnected and moving as one with smaller drones below the bigger drones like legs,” one of the sources familiar with the pilot’s witness account tells CNN.

“If the airman really saw what he described — a formation moving in unison — it would be an alarming advance in Iranian drone capabilities,” the broadcaster reports.