How are sea shells formed?

»> They are basically protective shells of marine molluscs, soft-bodied animals. When they are born, a temporary shell forms around them, called protoconch. When the mollusk grows and reaches young age, the definitive shell begins to form, replacing the first…

When was the wheel invented?

»> The first representation of a wheel ever found by archaeologists dates back to 3500 BC – that is, 5,500 years ago – and was made on a clay tablet found in the ruins of the city-state of Ur, where…

What are fjords?

They are huge rocky valleys flooded by the sea, formations that appear on the coast of countries generally neighboring the south and north poles. “The dimensions of the fjords are impressive. Some exceed 350 kilometers in length, have walls over…

How does the octopus produce ink?

Reader question – Rubens Camargo, Jataizinho, PR DARK CURTAIN The ink serves to confuse predators. The octopus measures the amount ejected in case it gets into more than one mess a day. A small animal, measuring around 20 cm, stores…