Yellow Cup Coral (Tubastraea sp.)
The corals on the page are most likely Tubastraea coccinea ヒメイボヤギ and/or Tubastraea faulkneri イボヤギ. They are both Yellow Cup Corals that look much alike. I am not sure what the differences between them are. They both are found under ledges and have yellow to orange tenacles. They are about 1cm across. Amami 2023
Yellow Cup Coral. Amami 2025
Yellow Cup Coral. Amami 2025
Yellow Cup Coral. Niihau 2019
Yellow Cup Coral. Niihau 2019