This Tarantula Species Has a Weird, Deflated Horn on Its Back | Smart News| Smithsonian Magazine
The 10 Best Horns In The Animal World: The Definitive List - Modern Farmer
Pronghorn with unusual horns – On The Wing Photography
Just a weird phenomenon - the way insects (I guess termites?) are eating the outer part of these horns and leaving strange protruding structures - bonus if you can guess the location! :