The New Scientist discusses what scientists are learning from 500 million year old embryos, and lo and behold, it matches what creationists would predict – that the mechanisms we use today were in place in antiquity, exactly as they are now. 

Computer-processed X-ray images of the fossils, which measure less than 1 millimetre in diameter, show previously unseen structures inside the ancient embryos. Researchers say the images show the ancient embryos had already evolved the style of cell division used by modern embryos.

Also, note the uncertainty regarding whether or these fossils are of the "proper" evolutionary age – while evolutionists wave this away as normal questioning for science, those of us who have been told that macro-evolution is fact can now see the paucity of data that such claims are made upon.  The truth is, they could be entirely incorrect – which is fine, but they fail to admit such, of course, being (evolutionary) believers and all.  I’m serious.

Two key features present in modern embryos were absent even in the
fossils containing 1000 or more cells, however: an outer layer of cells
called the epithelium and a fluid-filled cavity called a blastocoel.
That leads Hagadorn and Xiao to conclude that the embryos came from
animals more primitive than any living today, including sponges and
jellyfish.

This would appear to contradict
the findings of a previous study that concluded some of the fossils
were primitive animals that exhibited bilateral symmetry, a key
evolutionary development (see Tiny fossils reveal key step in animal evolution).
But Hagadorn says that the few fossils which looked bilateral had been
damaged, and insists that embryos with advanced symmetry are unlikely
to have evolved in time to be deposited in rocks of that age.

Although
the most accurate dating can only estimate the age of the embryos to
between 635 million to 551 million years, the earliest conclusive
evidence of bilateral symmetry is in trace fossils that did not appear
until the end of that period.