Some of the lines look as though they are raised. Run your finger over them and if the are raised they are just casting marks as mentioned earlier. Can you look at them with a magnifying glass or a magnifying app on your phone. If they are cracks talk to Subaru as they appear to helpful compared to my experince here. I knew a person who worked at Subaru in the EJ engine days and he said they had a lot of problems with castings as some were porous.