I've never seen those in real life before. I believe they are a sign of severe weather, and they certainly look quite strange for sure.
I'm not saying it was aliens but-
Seriously, though, very interesting formations there.
We've had those here a few times. It's always a run/duck/take cover when those come through, usually because we're walking the dogs when we see them.
Every time we've seen those the weather takes a nasty turn.
Seeing them in RL is downright freaky.