Final answer:
The magnetic compass was developed around 1000 CE and played a crucial role in the navigational revolution of Europe in the 15th century.
Step-by-step explanation:
The magnetic compass was developed around 1000 CE by the Chinese and later adopted by medieval Europeans in the 11th century and Muslims in the 13th century. It was a tool that had a magnetized needle floating in a pan of water, pointing north and south. Although it was useful for navigation, it was not always accurate because it showed magnetized north, not true north. The magnetic compass played a crucial role in the navigational revolution in Europe during the 15th century, allowing sailors to venture into the open ocean.