I just love these things. They're like velveteen agates. They're really common, found all over the world.
I know I have a deep affection for these, but I didn't realize I've been taking pictures of them every single time I came across them. I was looking for something else in some older images, and kept finding more pics of these, so I rounded up some of my favorites. These were all taken over the past year. Some are technically crappy, but look at the colors.
I'd like to know what causes the stripes and the different colors. The green one has algae growing on it, so it's excused.
Personal favorite is the golden one, near the bottom.