what do you mean by LR rubble area??
Take a look at this picture
from my gallery. This is the pod pile from the eBay detrivore kit.
What are POD's? What are they supposed to do?
They eat stuff in the sand bed, feed fish, are generally quite beneficial to the marine system.
Copepod & Amphipod Profiles
crustaceans are peracarid crustaceans, typically ranging in size from 2 to 50 mm, although a few may be larger. Amphipods are common in aquatic ecosystems throughout many parts of the world, inhabiting marine, brackish, and freshwater environments. A few species also live in terrestrial ecosystems. The order Amphipoda, which contains nearly 7,000 described species, is divided into three and sometimes four suborders: Gammaridea, Caprellidea, Hyperiidea, and Ingolfiellidea. The latter, however, are probably highly specialized gammarideans and therefore do not merit recognition as a suborder.