Nice atmosphere; Potential for more variety
The piano sound used has a very nice mood to it. Quite eerie yet adventurous at the same time.
The 'beeping' instrument line that starts at 1:13 would sound a bit better if it had slightly more reverb on it, because it doesn't seem to blend into the mix very well. It feels out of place and it has a negative effect on the atmospheric beauty that the rest of the music sustains.
I think that you could have added another instrument to this. Perhaps a low cello, or some sort of low brass/string sound? Something to give it a feeling that we are viewing a very vast cavernous scene, full of dark mystery and wonder - like in the Inception soundtrack. It would also provide more contrast throughout the mix, making the higher notes sound more prominent and grounded at the same time.
As usual your music has an atmospheric quality to it that I quite enjoy, making it a pleasure to listen to.
P.S Indeed.. that is a snail.