Crab feathers

A young crab, in her fresh, new outfit after a molt, came to the front of the tank, begging to have her photo taken.

Green shore crab, Hemigrapsus oregonensis, aka "Lady Bird"

The green shore crab has tiny hairs on its legs, which are usually a bit grungy, a bit frayed, somewhat coated with algae. But fresh from a molt, they are white and clean.

And I hadn't noticed before, but they're not just hairs. They look more like feathers, with a strong shaft and branching fibers.

Zooming in. I've darkened the background to show up the structure. (Click for full-size photo.)

No wonder they pick up so much detritus!