When cores arrive in the lab from the drill floor, scientists and technicians study physical properties of the rocks (magnetism susceptibility for example).
Magmatic rocks contain ferromagnesian minerals (see previous enigma). During the cooling of magma, the rocks, with such minerals can ‘fossilized’ the magnetic field. Some rocks from the oceanic crust are very amazing.

The rocks are not all able to frighten our compass when you approach it near rocks. Several measurements are performed in the laboratory of JOIDES. Some seek to know the magnetic susceptibility contained in each sample.
Sensors, in the lab, detect magnetism more or less strong for some samples. These physical data help the specialists team (‘PaleoMag team’) on board the JOIDES to choose their samples for further measures on magnetism trapped in the rocks.
Nice data to come ! But do not forget our weekly enigma !

Look at this picture below :

It is the image of a small device consisting of a magnet, a nickel alloy wire, a candle. The small ring of nickel is attracted by the magnet.

What will happen when the candle will be lighted ? And … why?