1 - you can get it before it reaches the spikes.
2 - I don't know what you've done, but you are able to get an item from below the spikes. Like here if a letter appears where the spikes are you can simply jump from below and get it, but if you throw a bomb you will die on the spikes. And here you can't reach with normal jump, but you can use a bomb to reach the letter, safe for you.