I've always wondered about the earth tentacle terror-of-the-most-terror Meridia-come thing. They're present in nearly every Ayleid ruin.
I'd assumed that, in every case except Abagarlas, those roots were just regular roots. None of the ruins are in very good shape, after all, so I think it's reasonable enough to assume that surrounding roots could have pushed their way in all on their own. The plant life in Abagarlas is much more plentiful than the roots in the other ruins, too.
Interestingly, when I went to look up the name of that ruin in UESP, I found this quote on http://www.uesp.net/wiki/Oblivion:Sideways_Cave:
The official Prima guide lists Sideways Cave in its Freeform Quests section as one of the more interesting dungeons and has this to say about the tablets: "Can you put it all together? The big picture is that, long ago, Ayleid settlers stumbled onto this grotto. They made it their own--in the end, too much their own. In doing so, they uncovered a forgotten shrine to the Daedra lord Meridia. Meridia's vengeance for this violation was swift: She crushed Abargarlas with her stone roots and, incensed that some survivors escaped, buried the grotta almost entirely."
And yeah, I know, the canonicity of that is dubious, at best.