Beware of the blob—this time, it's for real. As sea temperatures have risen in recent decades, enormous sheets of a mucus-like material have begun forming more often, oozing into new regions, and lasting longer, a new Mediterranean Sea study says. Up to 124 miles (200 kilometers) long, the mucilages appear naturally, usually near Mediterranean coasts in summer. The season's warm weather makes seawater more stable, which facilitates the bonding of the organic matter that makes up the blobs. Now, due to warmer temperatures, the mucilages are forming in winter too—and lasting for months. Until now, the light-brown "mucus" was seen...