That's an asterism, an almost entirely obsolete punctuation mark. It consists of three asterisks arranged in a triangle (the point can be at the top or the bottom) and it shows a break in the text.
Sadly, after only a few hundred years of use, people realised that an even better indication of a break in the text is, well, a break in the text: and so asterisms almost entirely died out.
Hang on, I really didn't need that asterism, did I? Bother!
The asterism is also sometimes used in place of a title (of a piece of music, for instance) or of an author.
While we're here, an asterism can also be either a star-like effect seen when you shine light into a gemstone, or group of stars that are easily recognisable from Earth but which don't make up an official constellation. Orion's belt is a well-known example - and, rather neatly, it also consists of three stars.
Piece of Almost Entirely Useless Information To Treasure Today: asterism. This word comes from the Greek asterismos arrangement of constellations, from astēr, star.