As D.C. juveline car theives are snatching cars for joyriding at alarming rates, police in Calvert County are not pursuing the case of the mysterious seahorse sculpture-napping that appears to be teenage prank. The beloved statue was outside the Adams Ribs restaurant near Prince Frederick earlier this summer when it was stolen. The sculpture is back, the Post reports, found dumped behind the cafeteria at a county middle school, where a group of the school’s…