Astronauts aboard the International Space Station are set to welcome a most unusual guest, as “the Blob” blasts off into orbit on Tuesday.

An alien on its own planet, the Blob is an unclassifiable organism – neither fish nor fowl. Nor is it plant, animal, or fungus.

As such, Physarum polycephalum – a type of slime mold – has long fascinated scientists and will now be part of a unique experiment carried out simultaneously by astronauts hundreds of kilometers above the Earth and by hundreds of thousands of French school students.