While they display a variety of growth forms, from disk-like to branching,
the typical archaeocyath skeleton resembles two ice-cream cones,
one inside the other, connected by vertical and sometimes horizontal plates,
septa and tabula respectively. The
ESEM (environmental scanning electron microscope)
image to the left shows the the outer wall and inner wall of one specimen
connected by six septa. The
ESEM micrograph to the right shows an outerwall and two septa.
The space between the inner and outer walls is termed the intervallum.
Nearly all of the primary skeletal elements
(e.g., inner walls, outer walls, septae, and tabulae) are perforated by small
Archaeocyaths were attached to the substrate by a basal holdfast
consisting of several prongs, or more commonly, a solid mass. Archaeocyath
fossils range in size from as small as a millimeter to well over one-half meter,
but typically are on the order of one to three centimeters. Skeletal material
consists of interlocked microgranular polyhedra of calcium carbonate
(presumably calcite) with randomly oriented axes, and
spicules are lacking.
Debrenne, F., A. Rozanov and A. Zhuravlev. 1990. Regular Archaeocyaths: Morpholggy, Ontogeny, Systematics, Biostratigraphy, Paleoecolgy, CNRS Editions, Paris. 218 p. + pl. XXXII.
Debrenne, F. and J. Vacelet. 1984. Archaeocyatha: Is the sponge model consistent with their structural organization? Palaeontographica Americana, 54: 358-369
Debrenne, F. and A. Zhuravlev. 1992. Irregular Archaeocyaths: Morpholggy, Ontogeny, Systematics, Biostratigraphy, Paleoecolgy, CNRS Editions, Paris. 212 p.+ pl. I-XXXVIII.
Debrenne, F. and A. Zhuravlev. 1996. Archaeocyatha, palaeoecology: a Cambrian sessile fauna. In A. Cherchi (ed.), Autecology of Selected Fossil Organisms: Achievements and Problems. Pp. 77-85. Boll. Soc. Paleont. Ital., Modena.
Kruse, P. D. 1990. Are archaeocyaths sponges, or are sponges archaeocyaths? Geological Society of Australia Special Publication, 16: 311-323.
Rowland, S. M. and R. A. Gangloff. 1988. Structure and Paleoecology of Lower Cambrian Reefs. Palaios, 3: 111-135.
Savarese, M. 1992. Functional analysis of archaeocyathan skeletal morphology and its paleobiological implications. Paleobiology 18(4): 464-480.