One offshoot of C. linkteneresca migrated westward into the shallow coastal areas. There they found an abundant community of thriving life... prime for devouring.
Like their ancestor, interwebs consist of four-cell clumps in which each cell has a tentacle that reaches outward. These tentacles can hold on to other clumps' tentacles, allowing them to connect into a large web, in which each clump is held far apart.
Interwebs, however, specialize in growing across the gaps between two hard objects. This may be stones, or at a small scale, individual grains of sand. However, immobile life forms provide especially good platforms. For example, interwebs may grow among a crystal grove's roots and crystals and the seafloor itself. This may even benefit the host, as the interweb does not eat the host but may eat would-be consumers. Other common hosts include shellstars, caltrop crystals, crystal bushes, binucleus crystal shrubs, saltrops, and landfall groves (the latter two only when underwater).
Interwebs typically grow as thin webs. Their tentacles produce sticky chemicals, which cling to the anchoring object on each end. They also stick to prey. The tentacles also emit fragrant chemicals as bait, smelling like food. Individual cells floating by are easily ensnared, the nutrition passed along from cell to cell. But larger prey may find itself caught in the web too, which holds fast to it and secretes digestive enzymes to absorb it. As the web is so diffuse, it may be hard to detect, but it can contract around large prey during a feeding frenzy, leaving just a few cells at the edges as anchors to make it easier to return to their original shape afterwards.
To find these gaps, the interwebs' sensory system is fairly sophisticated for undifferentiated cells. They find the solid surfaces by feeling with their tentacles, and the cells communicate chemically with one another. Once receiving the stimulus that suitable surfaces have been found, they stick to the area. They form lines between the surfaces, whether by congregation or by binary fission. The clumps will keep reproducing by binary fission (the four cells in a clump splitting simultaneously) until the gap is filled.
Webs as a whole may reproduce by fragmentation. When the two surfaces get torn away from each other, or a would-be prey item rips through the web instead of getting caught, individual cell clumps are liable to scatter far and wide, searching for a new suitable location to congregate. (The cell clumps are certainly capable of independent survival, which they do by luring and preying on single-celled organisms.)
But interwebs have an additional reproductive trick. After gorging themselves on a particularly large meal, they may contract further inward so that the cells are touching. There, they form a fruiting body, as the outer cells form a protective layer, and the inner cells spill open, sharing a melange of genetic material and nutrients. Once finished, the fruiting body bursts, emitting a series of spores containing newly formed cell clumps, which will go on to colonize new areas.