Lacrinopods

You already had a chance to meet these critters in the past: [link] but as you can see, there is some major overhaulin' going on. the most apparent difference is the number of legs and shape of the head, even though the internal anatomy also changed a bit.
These critters could be called "shark worms" because their teeth (even though miniature ones) grow throughout their entire life. The new teeth emerge at the front and push the old teeth further back, until the old teeth themselves get absorbed so the minerals can be used to grow more new teeth.