Snake Sea Cucumber (Synapta maculata) オオイカリナマコ
The Snake Sea Cucumber is long can reach over 2 meters. It is stiped and can be mistaken for a Sea Snake. I don’t think it would be mistaken for long though. It is soft sticky and very slinky like. Amami
2018
Around its mouth there are 15 tentacles for feeding. Amami 2018