The planet Donutus (named after the donut-shaped beings there) is home to many varieties of plants, animals, and…plantimals. One plantimal, the swimming bush, starts life as a worm. As it develops, its body curves back on itself and its digestive system becomes looped. The loops become more numerous until it forms a hollow ball of tangled loops. In adult form, the swimming bush has one mouth and no anus. Waste is cycled through the numerous loops and used as fertilizer by the photosynthetic skin, which is covered in leaves. The swimming bush swims by flexing specialized leaf-fins on its outer surface and perfects a bilateral symmetry, complete with frontward-facing eyes.
The picture at the top reminds me of the swimming bush, though it is irregular rather than spherical and has far fewer loops than a mature bush. I had thought it might be a detached part to be used as a mobile decoy to distract predators, such as the tails of certain lizards. It could also be used to distract prey. Without mouths, these detached parts cannot replace needed nutrients and can only live on photosynthesis alone for a few weeks. They sacrifice themselves for the good of the species.
The echinoderm in the upper right I originally thought might fill up with gas and float from place to place, dangling its poisonous tentacles for protection. Then I thought the tentacles might actually be snorkels to pull air down from the surface to fill the gas bladders in the first place. I thought modified tube feet might expel the gas in such a way to steer, zooming across the seafloor. Then I realized it should only have one snorkel (for its madreporite) and that any number of snorkels would cause a lot of drag. Then I thought that if the air was ejected at angles to spin the animal and the snorkel doubled as a feeding tentacle, it could create a whirlpool to suck in leaves, but then I remembered I already made a creature like that, except it uses legs to spin, which is probably more efficient.
The animal in the lower right has sticky feet and venomous horns. It lives in the reefs of planet Lup.