Blue shiny thing

That one shiny blue thing that used to be there… what were they called? What are they use for? I cant find them. But they are another struggle for sure 😭

Took me an hour to complete those moving through different platforms challenge💀 i had enough…. 😮‍💨 Why are they so slippery!?😤😡 there is no way for u to stop, u gotta make sure u land right huh!?… why.!😩