Stromatolite

 is an organism in Happy Birthdays. It is the first organism that the player will birth.

Birth Requirements
For Stromatolite to appear in the cube, there needs to a large amount of Zooplankton and a fairly high cube temperature along with a decent area of Shallows. Once those conditions are met, the player then needs to use the Broth of Life. After a little bit of time, Stromatolite should appear. During the story mode, it becomes available during the first episode: The Cube is born.

Trivia

 * Although the stromatolite is referred to as bunches of algae in the game, it is actually a sedimentary rock in real life.

Sources:
https://en.wikipedia.org/wiki/Stromatolite