Soft Unsegmented Lophotrochozoa without a Lophophore

OK.  You don't want to run away.  You don't want to eat and reproduce as fast as possible.  We're running out of options here.  You can either get help, or fight back, by eating other things, the bigger the better.  The improved nutrition from eating other, bigger, organisms will enable you to get bigger and stronger, but there is another choice - you can hide away somewhere with a decent food source and keep going on what you can eat in secret.

Big and bold.
Secret snacker.

Soft Unsegmented Lophotrochozoa

Slim and elegant, eh?  That's nice, but something's still got to change.  If you speed up the rate at which you get food, you will be able to reproduce faster, and your species will survive even though you get eaten a lot.

Stuff my face as fast as possible.
No!  I said slim and elegant.

Lophophorata

That frilly mouth of yours we just mentioned?  It's pretty good.  One of the easiest ways to evolve is to do something you've already done - but even more.

You grow frills on your frills!

The super-frilly mouth is called a 'lophophore'.  You can hide away in the mud, and slide out your frilly frills and quietly eat whatever passes by.  As time passes you adopt many shapes, but all basically mud-hiding, filter-feeding, hard little worms.