Red Moon Spring

Red Moon Spring is a type of Secret Room found in Lenile Cavern. It is found on floors 10-20 at all times, though you can only revive a fossil during Night.

It serves a special purpose and has a different layout than the common Secret Room.

Differences
Instead of the common Deluxe Boxes that are found in other Secret Rooms, this one offers no boxes. Instead, it can spawn fossil Pokémon if the player has the necessary item.

Pokémon
The Pokémon that can be found here are all the fossil Pokémon, depending on which Pokémon fossil they bring with them. This is a list of the fossils as well as what they spawn inside the Red Moon Spring:
 * Dome Fossil - Kabuto
 * Helix Fossil - Omanyte
 * Old Amber - Aerodactyl
 * Root Fossil - Lileep
 * Claw Fossil - Anorith
 * Skull Fossil - Cranidos
 * Armor Fossil - Shieldon
 * Cover Fossil - Tirtouga
 * Plume Fossil - Archen
 * Jaw Fossil - Tyrunt
 * Sail Fossil - Amaura

Fossil Locations
Fossils can be found in a variety of dungeons, but mainly Tanren Chambers. The fossils that are found in Tanren Chambers are all found in different chambers, and they are on the high floors (see Tanren Chambers for more information). The other fossils can be found in Mt. Skylift, Crystal Ruins, and Sentimental Aquifer. They are invisible on the ground of the dungeons, usually on the higher floors (see respective dungeons for more information).
 * Dome Fossil - Crystal Ruins
 * Helix Fossil - Tanren Chambers/Water
 * Old Amber - Mt. Skylift and Tanren Chambers/Flying
 * Root Fossil - Tanren Chambers/Grass
 * Claw Fossil - Tanren Chambers/Bug
 * Skull Fossil - Tanren Chambers/Rock
 * Armor Fossil - Tanren Chambers/Steel
 * Cover Fossil - Sentimental Aquifer
 * Plume Fossil - Tanren Chambers/Fighting
 * Jaw Fossil - Dragon's Descent Depths and Tanren Chambers/Dragon
 * Sail Fossil - Tanren Chambers/Ice

Recruitment
When you summon the Pokémon via fossil, the Pokémon will be the living counter-part of the item as a level 25 base form, with a recruitment of +1000 (always recruitable). Make sure you are using a Pokémon that is above that level when recruiting.

Trivia

 * The time for Red Moon Spring changed a lot during the game