Happy #FossilFriday! Meet Monodon monoceros, an extant member of the order Cetacea. You might know it by another name... the narwhal! It's sometimes called a sea unicorn because of its enormous tusk—actually an elongated canine tooth that can grow to be nearly 10 ft (3 m) long. pic.twitter.com/645Pb61i3J
人間と同じように中に歯髄が通ってるから、折れるととんでもない苦痛を感じるし、折れた部分から雑菌が入って死んでしまうことすらある。