This looks to be a setup for ʻōpaeʻula Halocaridina rubra native to anchialine pools in Hawaii. These brackish shrimp have been the focus of many experiments regarding closed ecospheres though many such as those sold online have failed, though many are successful like this one. The sea fan is a dead specimen.
There is a chance that some of the original shrimp may be alive in the biosphere as lifespans of 20 years have been recorded in some specimens.
