Crassula aquatica

About

Crassula aquatica is a succulent plant known by the common names water pygmyweed, common pygmyweed and just pigmyweed. It is an annual plant of salt marshes, vernal pools, wetlands, and other fresh to brackish water bodies. It is at least partially aquatic, living in areas which are submersed much of the time. It also lives along muddy banks and in tidally-active areas of estuaries.

Summary from Wikipedia