I wouldn't be so sure about that.

Take Boulder Downs, for example. There is something impaled into the centre of that formation, which is long and straight, suggesting they may have been impaled deep into the ground. It is likely the tip of one such "key".

While the coil may be occuring in various chambers related to Dalamud debris, it is highly plausible that these are partially in and around the spikes. It doesn't have to be one or the other.