I've noticed that they are candy hearts and say messages on them. I think over time the messages grow more kinder or whatever. I didn't get a screenshot of them, but I'm just putting this here so people can remember to keep an eye out for them.
I don't think the messsages get kinder. I've clicked >50 Golden Cookies since the update came out until now and I think that which message you get is randomly decided. I keep getting the same messages even though I've clicked a lot.
I'm not sure if I'm correct, but I think the golden cookies are constantly growing and shrinking like the normal ones, but the wrath cookies are kind of steadily growing with a little static. Just a guess.