This mound is home to a colony of marine worms, Dodecaceria, probably D. fewkesi. Here, the worms have retreated, it being low tide, into their calcareous tubes. Their tubes are embedded in a matrix of cemented sand particles. When the tide returns, they’ll poke their tentacled heads out to feed. A version of the photograph below appears on my Worms page. Like most images in theoutershores’ posts and pages, I cropped it to achieve something the original didn’t.
Before the crop: The original framing makes the colony look like a snowcone.
After the crop: I cropped the image from the bottom right making it less symmetrical. The crop eliminated the shaded, lower part of the colony, resulting in less contrast between top and bottom.
Cropping isn’t free. I had to give up on several interesting tubes, and the shape of the right side of the colony is now a mystery to the viewer. The eternal question is, was the crop worth the cost?
I wrote about Dodecaceria in Construction on the Coast. There, you’ll find more photographs of their colonies and the habitat that suits them.
If you walk Pacific coast shores and are partial to intertidal marine worms, I invite you to take a look at my Worms page. Before you visit I want to warn you, it’s new. It now features only three species (but three good ones), Dodecaceria among them.
theoutershores 
It’s cost free surely? You keep them both. They each have their part to play in your fabulous collection of shots.
Excellent point, Margaret. You’re right, free to me. I guess one of the costs is to to the viewer. They lose out on the information cropped out of the the original and they don’t get to weigh the tradeoffs. I was thinking, to some extent it’s the viewer that matters. I But in the end, you’re right. Thanks for challenging me to think about this!
I must agree with Margaret and you – win/lose – but you are free to keep both! Nicely done!
Thanks! Such a fun challenge.
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I agree with the others, too!! I think you can try a third shot up very close to the tubes.
Great idea, Patti. Thank you!
šš
Excellent.
Thanks so much for this illustrated post (and others). I was looking to identify the colony of tubes I photographed recently at low tide, and this is it. I appreciate the information!
Hi Ingrid, I’m glad you found something helpful, but I want to apologize for letting your note slip without acknowledgement. And I was just checking out your great website and blog. Probably just me, but how do I follow?