Definition: A landform consisting of loose rock particles such as sand, gravel, shingle, pebbles, cobble, or even shell fragments along the shoreline of a body of water.
Definition: A built-structure inhabited by an organism and essential to its survival, but not part of its body, composed of hardened (either rigid or flexible) secretions, with or without the addition of embedded particles, with those particles either selectively collected from the environment or passively becoming glued during formation (pers. comm. Read, G.).
Definition: Skeletal support provided by hydrostatic pressure from a fluid filled cavity (e.g. the coelum) surrounded by muscles. Hydrostatic pressure provides skeletal support in sea anemones, jellyfish, nematodes, annelids, echinoderms, and other groups.
Definition: A structural quality inhering in a bearer by virtue of the bearer's being thicker or more closely packed together; pressed tightly together.
Definition: a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure
