The mystery critter, mystified even more.

Once again, a critter I thought I knew has first stumped me, then amazed me.

The mystery. What is this?

Under a stone on the upper intertidal zone at Boundary Bay, a hint of tentacles caught my eye. When I touched the sand, it disappeared, so I dug for it, couldn't see it, and brought home the whole handful of sand.

As first seen. My fingertip at top left. I've removed the colour from most of the photo to highlight both the one I saw and the other one that turned up later.

At home, in a bowl of seawater. There were two of them, about an inch and a half long.

Were they worms? Peanut worms could be shaped something like this, and have similar tentacles. Or were they anemones? But the body didn't look like an anemone stalk.

A hint; the tentacles have those heart-shaped marks.

I've looked and looked, and looked: the only tentacled beasties I find with the heart markings are Anthopleura artemisia, the burrowing anemone, like the one that came home with me from Campbell River.

But that long, worm-like body?

Placed in the aquarium, they lay on the sand, withdrawing then extending their tentacles.

Tentacles partly extended.

I have been Googling for days. I find oodles of conflicting information: the burrowing anemones are not "True" anemones; they are so; it's only the Burrowing Tube anemones that are not "True". The local burrowing anemone, Anthopleura artemisia, does not have a long, worm-like stalk; it is "capable of greatly elongating.". It has a base on the stalk that "glues" it to a solid object; it has a bulbous, muscular base that anchors itself in a burrow. (I think the tail of my critters is remarkably bulbous and muscular.) 

There is a smaller burrowing anemone, the ten-tentacled anemone, a true anemone with similar markings on ten tentacles. My critters have more than ten tentacles.

Of the local anemones, only the Burrowing Tube anemone, Pachycerianthus fimbriatus, in a separate Subclass altogether, makes a tube. (Pachy doesn't look at all like my long-bodied anemones.)

Oh, and they like stone and sand mixes. But they don't; they want fine sand only.

The more I read, the more confused I get. I give up; I'll just report what I see.

One of the little anemones, contorted as they do, feeding.

The critters lay on the stones, contracting and squirming occasionally. They had been found buried in sand, so I buried them in sand. They worked their way to the surface, and lay there practicing their Yoga positions, until the current swept them away to another inhospitable location. I gave them more sand; they abandoned it.

One eventually found an oyster shell with a half-teaspoon of sand in it; he settled in, buried the bottom segment of his body, and started to feed. For a day. Then he upped anchor and coasted around the aquarium, checking out several possible spots on the way. Now he's back in the shell, and looking as if he's planning to stay.

The other one found a place, buried himself completely out of sight for a couple of days, then sprouted tentacles. I thought he'd acclimatized, but this morning he moved out, floated around a bit, then parked beside his big Campbell River cousin. He's there now.

Wanderer # 2, waiting for a lift.

At the left, above, you can see the hint of tentacles, retracted into the body, and the cross-hatch muscles. Those constricting rings move up the body slowly, as if it were a balloon with an elastic band being pushed along.

Wanderer # 1, jammed between two shells at the edge of the oyster shell he likes. At least half of the body is buried, the tentacles retracted.

If, as it seems, these are the same species as my Campbell River Refugee, "Val", then I am more astounded by him than ever; when we found him he was just a round blob of tissue. There was no hint of a long body, no column. And he's regenerated himself from that remnant!

Val, today. Enthusiastically feeding, and almost completely healed.

Update: in the comments, Tim suggests another species, to be found on this West Coast: Flosmaris Grandis, the White Burrowing Anemone. At least the shape is right, but I see no hearts on the tentacles.