The only complaint I have here is that there is no prominent openings of the mouth or nostrils. And, no eyeballs. Also, the poly count could have been reduced between the tail and back of the sponges, and between some sponges too, it seems to me like there is a tad bit too much topology there.
Other than that, I love the texture work and the normal maps look amazing, especially the scales on the belly. Great work, keep it up ^^