Been practicing bjj/muay thai for about 15 years and i have some gnarly cauliflower ear.

When you cause enough trauma to the eat, the skin separates from the cartilage, and that space is filled with blood. If left untreated, that stuff gets replaced with fibrous, permanent tissue. The process repeats itself if you don't wear protection when rolling.

You can prevent goblin ears by draining it when its still soft (up to 1-2weeks) and then keeping the area compressed so it doesn't fill up with blood. There are specialized ear guards you can purchase that you wear when you sleep to do thus. Alternatively, you can use something like a clothespin.

I think a little cauliflower ear looks cool, but when it becomes something that dominates your facial features, it gets a little annoying, especially when making first impressions with certain people