The mireworts are a species of small (piglet sized) motile (snail paced) autotrophs that have a high degree of intelligence and sociality. They gain energy solely through photosynthesis, and consume only small amounts of material to obtain minerals not found in the air and dust they breathe.
As small and slow and edible and available in feast-sized settlements, lots of (unitelligent) predators on their planet would like to eat them such as the direworts (a wolf like creature).
They are epiphytes so I thought might form colonies on protective walls they have built. But for the mireworts, who are photosythetic, walls might blot out the light they need to feed if they are on the inside. And being on the outside, well...
What alternative systems could these mireworts construct to protect themselves?