Ha! What a wonderful story! I LOVED it! This is one of the rare, rare, rare occassions in which someone has played the Lovecraft notes and managed to make music with them. From the scientific main characters, to the academic tone (which was never hard to follow - although I am fairly familiar with pre-Cambrian life myself) to the slumbering horror awakened by those who would pry too deeply - this one did it all.
The language was absolutely wonderful and I was enchanted by the Lovecraftian prose which, nevertheless, managed to avoid his usual diatribe of "unspeakably" superfluous adjectives. In general, it was more adroit than Lovecraft, for which I must praise the author mightily.
...that being said, I think it actually suffered a little (and this is just my opinion) for not delving into pulpiness enough. Act 1 was a little slow and dull (especially compared with Act 2 and 3). I would have liked to see a little bit of "telegraphed" ending to keep us on our toes and build some dread through the otherwise hum-drum beginning.
Also, personal opinion here, but I would have liked to see more of a hint of the larger creature below. I realize a huge yellow, squid-like eye with square pupils, swivelling to fix on our poor scientist as he (foolishly - and in absolutely spot-on Lovecraftian fashion - delved into the excavated pit) would not have fit in with pre-Cambrian life, but something big and shocking (similar to the reveal in "The Shunned House") with which to preface the flow of hydroid (GREAT word) horrors would have been appreciated. But, then again, that's my opinion.
Finally, my one other nit-pick might be that, although the horror escaped, the majority of it was destroyed. Never end a Lovecraft story like a Jason movie - the horror should not escape, it should merely hint at far, far, far WORSE to come. The secret of the abyss is always that it conceals, at its heart, a darker and deeper abyss.
But those minor things aside, this one was fantastic. Great job and great choice for PP.
EXCELLENT reading by Al, too. It's no small feat to speak clearly a thick, heady diction more fit for being chewed upon.
(Apologies for the breathlessness of this review, but it speaks to how much I enjoyed this story.)