Earlier today, I discovered fronted adverbials. So here, 'earlier today' is a fronted adverbial. Here are some more examples. Calmly, the family sat together and watched a movie. Like a cheetah ...

Adverbials are words or phrases that give more information to the sentence. "I discovered fronted adverbials, earlier today." 'Earlier today' is the adverbial. "Earlier today, I discovered fronted ...