Has my friend found a rare species of sea slug?

[Poppy]

My friend found this odd little sea slug when she went to the beach the other day. She lives in Skye an island on the West Coast in the Highlands of Scotland and i'll just write how she explained it looked like. She said it was the size of her thumb, was bright pink and had little tentacles on it's back. She said she found it in a rock pool and put it in a jar and tried to take it home. And for some reason, she put her sock in the jar with the sea slug and when she got home, the sea slug was sticking to the sock and when she tried to remove it, the tentacles tore off it. I know she wasn't lying when she told me this, so could you help me find out what kind of animal it was?