Okay so i call these things as the tree worms. They are just really strange alien animals.

-they use their flappy frill things to photosynthesize, breathe and to catch bacteria and small insects and animals from air
-the frills are covered with thin layer of slime
-when they have enough food caught on a frill, they pull the individual frill inside and eat everything useful from it and then push it out again
-their tail (exterior part of worm) is covered with thick bark-like skin and small breathing holes (it uses them to breathe when the frills are pulled inside)
-the worm can crawl around on ground but they prefer to keep their most vulnerable part underground so they come fully out of ground only in emergency situations
-they use their arms to keep themselves in ground or to crawl around
-they might use their tail to smack animals that are threatening them