vibrating spider

I dreamt there was this strange, very large, yellow spider in the room. I wanted it gone, but at the same time I was curious, so I didn't throw anything on it. It was a bit larger than a baseball (including the legs) and had very long pointy legs. It would move fast from one room to the next, but when it changed directions, it would do a backwards summer-salt, which would make me laugh. Then it would curl into a ball and vibrate. When it did this, it's legs were thick like a tarantula. A friend walked in and found an animal died that she loved and she was crying... then her sister found out and she was crying. I was sad for them, but concerned about the spider. I decided to show it to them, because I thought at least maybe the summer-salts might lighten their mood. But it was still scary...