Among the most important and prolific sea creatures, diatoms are unicellular algae that exist singly but can join to form colonies. Characterized by a silica shell of often intricate and beautiful sculpturing, they are found in fresh and salt water, in moist soil, and on moist plant surfaces. As the principal constituent of plankton, diatoms are an important food source for many aquatic animals. The shells of dead aquatic diatoms form what sedimentary material used in the making of dynamite?
Back in the day
After staging Polish attacks on German forces to create the appearance of Polish aggression, Germany invaded Poland, beginning WWII. Britain and France declared war on Germany two days later, and all the members of the Commonwealth of Nations, with the exception of Ireland, rapidly followed suit. The German blitzkrieg crushed the Polish defenses. Within a month all of Poland was occupied by German forces as well as the forces of what state with whom Germany had just signed a non-aggression pact?
Born on a day like today
Marciano turned to professional boxing in 1947, after failing to become a professional baseball player. On his climb to the heavyweight title, he became the second boxer ever to knock out Joe Louis. He won the title in 1952 and defended it 6 times before retiring. The only heavyweight champion with a perfect professional record, he was undefeated in 49 fights—43 won by knockout. A test of the force of his punch found that it carried enough energy to lift how much weight one foot off the ground?