Are bubbles will clog the small pours in the sponge, causing it to slowely soffocate. Air is not something you want to get in contact with the sponge.
FWIW,
Sponges do not have any zooxanthellae, and are therefor, non photosynthic. They do best with low amounts of lighting, to prevent any algal growth to start forming on the sponge. Algae will clog the pours of the sponge, causing that area to die off within a matter of weeks/months. Sponges will require strong amounts of currents to discurage any algae growth, as well as help with the filter feeding process. Most likely, I wouldn't worry about the sponge too much.
MichaelTX,
Your 'Sponge' actually resembles the form of a species of Limpit, rather than a sponge.
Graham