| Why did some of them choose infaunal life at approximately the same time that other organisms developed mineralized skeletons? |
| If so, the oldest traces of locomotory activities of the metazoans should be connected with their infaunal life. |
| Within a particular paleoenvironment the organisms could further subdivide resources by establishing epifaunal, and possibly infaunal, tiers. |
| Marine invertebrates include ammonites, echinoderms, bivalves and crustaceans, but infaunal elements are rare. |
| Life habit categories included epifaunal, infaunal, shallow infaunal, and deep infaunal. |
| Lingulids are shallow burrowing infaunal filter feeders of the shallow intertidal zone. |
