Margarito did the same damage as a careers worth of wrestling to lujan's ear in a single fight...then he hit it so many times it started to come off.
http://fightstate1.devise.netdna-cdn.com/wp-content/uploads/2015/08/sebastian-lujan.jpg
All stated about wrestling and rubbing on each other is true. The ears I believe fill up with blood and if it isn't drained, it causes the permanent dis-figuration.
Honestly, the only time I've seen a boxer encounter this DURING a fight was Pacquiao-Cotto. Pacquiao ate some brutal shots by Cotto. The post fight interview shows his ear completely swollen and disfigured. Lucky for him though he had that taken care of as soon as possible to prevent as much dis-figuration as possible. If you see him in fights/interviews after the Cotto fight, his ear is still a little whack but not as bad had he not gotten it taken care of.
Pull yourself out of a tight headlock and often times your ears take the most damage. Take a knee to the side of the head/ear and that'll grow some flowers.
Wrestling/grappling is bad on the ears. You're always banging your ears into guys' heads, getting your head grabbed and twisted, etc. You don't see that in boxing.
It's why amateur wrestlers wear those ear-guards.