I’m not entirely sure if this theory can be considered canon, but I think that the ammonite uses the pheromones as a psychological convincer to any random creature to defend it.
That’s just a theory, a GAME THEORY!!!
Don’t even think about hitting it. Just don’t. If you accidentally hit it, just swim away as fast as you can. I was out hunting for ammonites (I didn’t know what they did back then) on my basilosaurus. I saw one and hit it. I watched in horror as the whole ocean came swimming at me. I swam back to the surface, only to realise, a Tutsi was chasing me. It knocked me off my basilo and it tried to kill it. Luckily I had scuba gear. I got the gear on, whistled passive and put it to follow. The stupid tuso chased me around the whole map and now it is right next to my base. My basilo is stuck on the other side of the island. All because I hit an ammonite.
Ever met a cry baby?..This guy will wail if you hit it and will cover you in a type of pheromone gas....causing you to attract every dino, sea or land, to bite your butt. Prepare for war. You only need to survive 80sec.
This thing is the exact equivalent of that ‘cool’ girl (who is just a spoiled brat and good for nothing; If you get mad at this tip then it could mean you). Touch her once and then all of the school bullies (Tusos, mosas, plesiosaurs or the entire ocean) comes to beat you up. How do you fight them? A basilosaurus, I swear it works (probably the equivalent of a teacher giving detention to all of them) killing all of them. Trust me, basilo are tanks and good fighters and is not effected by eels or jellyfish. A few will do. Ride on one and the rest odder them to attack the tuso while you attack the mosa and then the plesiosaur then the smaller creatures.