Thanks for the comments everyone.
Yeah, the urchin shot....that corner is really hard to clean. I should have taken the scraper to it but was hoping the little bit of growth would blend away instead of what it did. The urchin was indeed carrying around this little piece of rock which drove me nuts but I wasn't about to try and remove it and risk ruining the shot....or getting stabbed by the urchin.
I also didn't want to crop the urchin shot any because that's the full frame...no crop on that shot...so I think cropping it might take away from the pic. Maybe I'll play with PS a bit and see if I can clone out the gunk on the glass.
I'm really pleased with how these came out....since previous attempts at tank photography failed miserably. I wonder though if my new lighting has any effect? I'm running VHO's now versus previous tanks that had MH or PC bulbs.
Oh, and as to urchins eating algae....while I can't exactly confirm it, I have had a LOT of algae (turtle grass and various bubble algae) disappear in record amounts after adding the urchin. But I also have an Atlantic Blue Tang and a few Mythrix crabs in there too.