Question: Which of these photos contain an image of a worm?
If you guessed the one in the center, you are only partly right. Actually they all are images of worms, specifically of the class of worms known as polychaetes commonly referred to as bristle worms. The one in the center is the only one that actually looks like a worm to me, but the other two are worms also and in the same class as the center one.
The photo on the left shows Christmas tree worms, “Spirobranchus giganteus” and the photo on the right is of a feather duster worm, “Sabellastarte spectabilis”
All these worms are commonly found in St. John waters. The Christmas tree and feather duster worms are usually found on coral reefs and on rocks. They will shoot back into a shell-like tube if approached too closely. The worm in the center is a fire worm and is found in shallow coral rubble waters often under rocks. You don’t want to touch one because the bristles break off and give a painful sting. (I once saw a dog that stepped on one, and it howled and cried for quite a while and wouldn’t walk on that paw for a few days)
BuzzFeed.com has some cool macro images of bristle worms. Check them out