A structure consisting of up to 35% iron compounds (iron oxides, iron carbonates, and iron hydroxides) that forms under water when wrought iron rusts. In appearance, it resembles an icicle or stalactite. The remainder of the structure is a complex community of symbiotic or mutualistic microorganisms, including bacteria and fungi, that use the rusting metal as a source of energy, collectively producing the mineral compounds as waste products and hence forming the rusticle. Structurally, the rusticle contains channels to allow water to flow through.They are very delicate, and easily disintegrate into a fine powder if disturbed. The outer surface of a rusticle is red in appearance while the core is bright orange.