The National Weather Service out of Boulder tweeted out a weird radar image on Tuesday afternoon over Elbert and Douglas counties.

A loop of the images show what looks like a rapidly growing amoeba in a Petri Dish (it wasn’t that).

Meteorologist Bernie Meier with Colorado’s NWS says it was most likely flocks of birds, although he couldn’t be sure.

“We're not 100 percent sure it was birds, just kind of an educated guess,” he said in an interview on Tuesday. “I mean it's not one huge solid flock of birds. Those individual pixels [on the radar] are like a quarter mile by a quarter mile.”

That's a pretty large scale. It's why the NWS thinks the growing mob could also be dust, or even insects that will appear on radar from time to time.

“I think of summertime, evening, the bugs and mosquitos come out so a lot of times we'll see activity increased in evening hours on radar with that,” he said.

Twitter users had other ideas however.

Kurt Sevits tweeted a scene from the movie The Birds by Alfred Hitchcock, that show dozens of birds attacking people on the streets.

Twitter user holy$wagg tweeted “STORM OF BIRDS.”

Other users thought the radar image was a product of migrating butterflies.

They are all possibilities but the NWS said the most likely outcome were birds. Because the radar image is so large, Meier says even if the birds are 100 yards apart they can still appear like a large flock on radar.