"...triangular objects that fell from the sky"

i.e  shark teeth.      They were used as amulets during the Renaissance, thought to be the petrified tongues of dragons or snakes, and to have the power to ward off snake bites. It was Pliny who thought they were "objects that fell from the sky" during lunar eclipses. While they have the strength to grind up a man, man has used them as tools to prepare food, as well as weapons, on daggers and arrows.
I remember finding one as a child, it was black, and smooth. But why shark's teeth, as a blog post theme?
I was thinking today of all those difficult things we experience as human beings, how much we can be hurt by those closest to us, by their shark teeth, if you will. This was one of the themes on this week's Parenthood, which I am convinced is written by a therapist. A mother turns 40, and her daughter skips out early to hang out with friends. The mother talks to her mother, who reminds her that she, too, ditched her 40th birthday all those years ago. We humans are inclined to take more notice of the thorns that wound us than the thorns we throw at others. Even if we do not do the same hurtful thing to other people, we still have our own brand of hurtfulness, our own Jaws.
The other day I had an interaction with an older student who approached me as an equal, and proceeded to denigrate the institution I work for, and some of the educational principles I stand for. She had received a different education in the interim - one that has its place, but not one that I would substitute for the whole of what education is, and should strive to do. I was so irritated by this encounter, for I could have stood to learn something from her, but because she took for granted what she was saying, she couldn't articulate the benefits of the education she received.
When I related this encounter to a friend, he said, you need to learn to be more pleasant. - Pleasant?! - Yes. I need to file down those teeth. Both in how I treat others and in how I treat myself. So, this afternoon, as I expect to see this student again, I plan on saying something welcoming to her, as a gesture of good will. And as for how I treat myself, I think I need to stop expecting people who call themselves 'students' or 'teachers' to be sensitive to objectivity. But if you've ever seen a shark's tooth, you know that it would take a long time and much effort to file it down!
But now on to the fun part: the shark teeth, while injurious, can also be put to good use if we learn how.
I will wear it, as part of my metaphorical jewelery collection, as a piece of sky. Every time I hear the dun-dun-dun-dun leitmotif of the approaching shark, I will remember my own set of pearly whites.
What I am learning about the scientist I am researching for my dissertation is that he was so successful in life because instead of rejecting alien cultural or scientific methods, he worked hard to study them first, and instead of critiquing what he felt was wrong with them, he would work constructively on what he felt was a better direction --- using the best parts of what he would otherwise critique (ex. he was not fond of technological development in his own country, but suggested using technology to teach students about agriculture during winter months).  The tooth becomes a tool.
And below is a picture collage for your aesthetic enjoyment. I call it Showroom: isn't it true that in our dealings with others, we should strive to present the best of ourselves?

Elements: paper bag, cabochons and medallion: pugly pixel;

retro frame: minitoko; ribbon: shabby princess.