Complex structures in a rusticle involve various means of retaining (and transporting) water, iron-rich plates, threads, and bundles, all within a very spongy pumice-like material.

The Titanic is covered with rusticles assuming many different forms including hanging (A), plate-like (B), branching (C), oozing (D), clustered (E) and folded (F). Both the hanging and branching have large dense shoulders attaching to the steel (A1 and C1) while the hanging has a large suspended appendage (A2) leading to a dense foot (A3) at the base.

Debris (glass, metal, coal and ejected clays) was ejected with steel from the Titanic and formed an ejecta blanket locked in place (or fossilized) by the rusticles. Stones from iceberg melts along with natural oceanic debris were subsequently added to the uppermost (or youngest) stratum.

This diagram shows a pathway through which the steel (1) can move into the rusticle (2) and be transported away as red dust (3) which settles back (4), on the seafloor (5) or floats away (6) moving downwards (7), upwards (8) or outwards (9) into the ocean. When the rusticle dies (10), iron moves to the seafloor (10) and may be used by the bacterial plates growing there (11).

Vertical sectional diagram of a hanging rusticle attached to steel plates under the shoulder. The structure is a mixture of iron-rich plates, porous media and water channels. These are located in the smaller diagram (lower right). Water passes in and out through the ducts which are connected to the upper and central water channels.

This is a drawing, under x40 magnification made using a stereomicroscope, of the structures observed on a fragment taken from the hanging appendage of a rusticle. There were four major surface structures. These were a filamentous coating of threads which extended out from the rusticle into the water, crystalline structures which extend knob-like out from the surface, resinous exudates which coated large areas of the surface, and ducts which perforated through the surface to the porous layers inside. These ducts led to channels which zig-zagged erratically through the body of the rusticle and appeared to interconnect with a central water channel. There were various reservoirs for water within the rusticle which ranged from small sack-like side-channels to larger cavities which appeared to be cavernous and larger than the sacks. On the outside of the cavities there were sometimes fibrillar bundles of stacked iron-rich columns. The whole structure was riddles with threads and some longer ones actually spanned the central water channel. These span threads appear to give some structural integrity to the whole body of the rusticle. Within the body of the rusticle were plates of iron-rich material surrounded by porous materials which were either pumice-like or very fibrous. The water channels permeated these zones.

Some of the common forms of rusticle growth are shown in this artist's rendering. These rusticles grow over the steel surface in a number of ways. The large hanging rusticles (A) are attached to the steel by a large dense shoulder (A1) with a freely suspended appendage hanging down over the side of the steel (A2). While this appendage is large, it is fragile and extends down wards to a dense foot (A3). Many flat plate-like rusticles (B) grow over the horizontal steel surfaces and are often covered with red dust. Other hanging rusticles posses many appendages (C). They, too, are attached to the steel by a shoulder (C1) and hang down freely but with many appendages (C2) which are also very fragile. Where the steel plates have been pulled apart, rusticles can be seen growing covertly within the gaps (D). Other rusticles attach tightly to vertical surfaces as spike-like growths (E) or large interwoven flat plates (F). All of these rusticles appear to have extracted iron from the steel at their attachment sites.

When the Titanic sank, the main hull pieces scattered debris as they fell to the seafloor. Some of this debris came down slower than the parts of the vessel itself and so rained down on the Titanic as it settled into it's final resting place (1). Coal, glass fragments settled on the ship (2). As the rusticles grow over these surfaces, the debris gradually becomes embedded in the growth (3). When the rusticles are overgrowing the debris, they are subjected to occasional bursts of falling stones coming from the melting icebergs above. The rusticles therefore become biological records of the events that occurred ate the sinking of the Titanic (the debris) and the subsequent iceberg melts.

The steel is bioextracted (1) by the rusticles where it is first concentrated in the body of the rusticle (2). Over time some of the iron is released as floating red floc (3). This may settle back on the Titanic and be reused by the rusticles (4) or it may settle close around the vessel where it is used by the bacterial plates (5) growing on the seafloor. Lighter red floc floats away from the Titanic (6) where it might fall downwards onto the seafloor close to the Titanic (8), move upwards towards the deep scattering zone (8), or float away on the currents passing over the Titanic (9). When the rusticle mature and become too heavy, or die, they may fall to the seafloor around the Titanic (10) and perhaps become incorporated in the bacterial plates growing on the seafloor (11).