The Secai Ruins are a stony, stalactite-formed ruins built in the center of a lake, containing the Shrine where Genki is unlocked twice in the anime series. Because of its location and look, it is also believed to be the second level of the Monster Rancher Battle Card game, which will allow you to unlock Gali's card after you explore all 6 levels. This would place it on the eastern side of Aurora Island.
The ruins have several lava pits in the lower levels, and a large statue of a Dragon is perched over the entrance. A powerful male Daina lives in the lowest level and serves as a level boss.