|Small prickly pear plant in a flowerpot?|
Rockweed grows right up to the high tide line on the south end of the Boundary Bay beach, just north of Point Roberts. But it's an unusual rockweed; small, brown, straggly plants, looking more dead than alive, each tiny plant attached to a stone small enough to be rolled around by any wave action. The curve of the shore must curb the energy of the currents here, for these to survive.
They survive well in the aquarium, too. Other rockweeds tend to disintegrate, probably because they've been torn from their moorings. These come home with the stone attached. They're not exactly beautiful, but the snails and hermits love them, for food and exercise both.
This turned out to be a branch tip of one of the weeds. To the naked eye, it looks brown, but the flash brings out other colours, red and green.
The blue "ball" is a periwinkle snail. One of its antennae is showing, to the bottom right.
And those white "cactus prickles"? Everything that's been in the aquarium for over a day, no matter how clean it was when I added it, (I scrub shells that I add, and the glass walls) develops a miniature forest of tiny algae and other organisms, hydroids, worm tubes, protozoa, with their resident mini-critters. Looking at any of them under a microscope, I always see scooting, busy copepods and transparent worms. Even smaller still are swarms of assorted diatoms. And over it, in the "atmosphere" over the "forest", larger copepods and baby amphipods dance.
At this magnification, maybe 4 times the actual size, and seen through algae-coated glass, the white spots would be copepods and amphipods. The fuzz on the circumference of the snail is probably made up of hydroids.