DARPA is funding reef structures that will be colonized by corals and bivalves

Navy sinks old concrete carriers in the Gulf of Mexico already, for this exact reason (artificial reef). i remember this happening at least 20+ years ago... it's not as new novel idea. Florida also uses shell material as aggregate in concrete already.

I'm not sure about the "concrete" part, but the final Essex class carrier, USS Oriskany, was sunk off Florida to form an artificial reef, the first US naval ship for which this was done, just about 20 years ago.

https://en.wikipedia.org/wiki/USS_Oriskany#2004_%E2%80%93_ar...

How does a artificial reef plan hold up to ocean accidifcation? Can you hold it back by adding base material that keeps the waters permanent habitable for shell-organisms?