Hydroskeleton

The wiki says wormacle because that page hails from a time when we thought we wouldn't be able to make an organism editor that is as detailed as we now think is possible, so the prevailing opinion was that we'd need function parts that are like spore parts but more flexible (in the sense of being able to be modified for use in more ways, though the wormacle also happens to be very physically flexible), which led to the concept of the wormacle, a flexible hydrostatic limb/spine which could serve as both a tentacle (whether tentacles like the legs of cephalopods, starfish, or, say, hallucigenia) or a worm-like body (for example, annelid worms).

Chances are, the wormacle will live on in the final organism model as a hydrostatic skeletal part -- needing to be little more a bag of water surrounded by a layer of muscle. Much as you can build an endoskeleton by linking together bones with joints, or rather, evolve a skeleton by developing a segmented structure containing multiple bones (or cartilage, or some other stiff pre-bone structure), then bit-by-bit evolve ligaments between them until you have a true connected skeleton; you would build a hydrostatic skeleton by attaching bags of water to each other, perhaps with valves or sphincters between them to allow further control on size and stiffness of any particular segment.