Uh-oh. Black mold.

[kimo wires]

Remove the baseboards. Cut Paint and caulk with razor knife, Insert pry bar behind nails and hammer outward on the other end of pry bar, not damaging the drywall above the base trim.cut the drywall out just below the baseboard line. You can then inspect the bottom plate for leaks,wet rot, termites and Mold. you can always replace the base trim with bigger trim if you need to cut up higher.