Guys, fellow marine enthusiasts and professionals. Today I stumbled upon these strange things and totally freaked me out. They were found in the gills of mud crabs I bought from my local fisherman. The mud crabs were healthy and alive when I bought them. When I was cleaning the crabs, I saw the ‘worm’ like organisms wriggling slowly. They were only located in the gills of the crabs, while other parts of the crabs were clear of these organisms. They were present in both female and male crabs, which I guess should not be baby crabs then? Please help me identify these things, thank you very much.