Megabalanus

Megabalanus is an acorn barnacle, a sessile crustacean that secretes a calcium carbonate shell consisting of five plates.

Other species are more select, such as M. californicus of tidal habitats in California and the greater North American Pacific Coast.

[4] Fossils bearing a close resemblance to M. tintinnabulum are preserved in large numbers in the Tabernas Basin of Spain.

A case study of this area showed that the state of preservation of the organisms makes possible estimating the distance they were transported post mortem .

Since the species today lives in the intertidal zone, this allows an estimate to be made of the distance from the shoreline, and by implication, the water depth.

Fossilised M. tintinnabulum (?), which grew on a boulderous debris fan (preserved as dark breccia, bottom), and were smothered by deposition of sands (orange upper layer), hence preserved in situ .