SpongeBob really was square...

A break from Doom:

[link to phys.org]

It turns out that the earliest sponges were not amorphous blobby things with no symmetry (as they are today), but were actually square. Living sponges must therefore be secondarily simplified relative to their earliest ancestors, having evolved to fit their mostly filter-feeding niche on the sea floor. This causes problems for interpreting the first animals, because it means that the earliest living metazoans were probably quite advanced... perhaps this puts the Ediacarans and placozoans back in the spotlight?