I've discussed peanut worms on the blog before (see post from 31 January 2013), but I haven't shown this species yet.
Remember that peanut worm tentacles are located at the tip of a long "introvert" that can be withdrawn, or rolled in on itself. Here's a series of pictures illustrating that process (below). Watch the tentacles disappear!
Themiste pyroides has wonderful golden tentacles, a purple "neck", and fascinating hooked brown spines — see close-up below. You'll laugh, but the shape of the spines reminds us of tiny chocolate chips!
Because peanut worms live in crevices, you often only get to see their tentacles. Look closely for clusters of golden tentacles extending from low intertidal zone crevices along rocky shores, and you may be rewarded with a sighting of Themiste pyroides!
P.S. In this species, the tentacles are used for suspension feeding — gathering small food particles from the water.