вполне обычное явление

it's not uncommon (to + do smth.: He thought it was a very big manatee, but something wasn’t quite right. “In these waters, it’s not very uncommon to see them,” Tiller told McClatchy News. “This one looked very different! It had huge muscles like shoulders on a bull! It was as if it was rolling its shoulders like a bear under water! We did not see any fur, or head, or hands and feet.”