Originally found only in the Indo-Pacific and along the eastern Pacific coast, they were likely introduced to the Atlantic Ocean in the 19th century through human activity and now has a global distribution.

[7] A 2021 study from South Korea found that triangle barnacles' mitochondrial DNA comprises 15336 base pairs and 37 genes with an order and traits similar to other Balanid species.

[6] The goal of both studies was to better understand Balanus trigonus' phylogenetic position based on the mitogenomes, though they yielded different results.

The Korean study, considering the mitogenomes of 28 barnacles, placed B. trigonus closest to a clade comprising Fistulobalanus albicostatus and Amphibalanus amphitrite.

[5][9] The Chinese study, however, considered 30 barnacle species and concluded that B. trigonus paired with Acasta sulcata.

In this species, the shell wall is made of six dark pink plates which are covered with white rib-like ridges as well as pores.

A flat-shaped and pore-covered calcareous basis forms the bottom of the shell and connects to the ground or material the barnacle is growing on.

The open top part of the barnacle shell which connects to the outside, the orifice, is relatively smooth and triangular in shape.

In living triangle barnacles, often only the scutum can be seen, and has up to six lines of small indentations caused by crossing furrows and ridges, whereas the tergum has a wide, dull spur which can take up up to half the opercular valve's width.

[4]: 224  He gave the species' range as including New Zealand, Sydney, the island of Java, the East Indian Archipelago, Peru, California, and what he called "West Columbia".

[13]: 66  The triangle barnacle's invasion started in 1867 in southern Brazil when a species since synonymized with B. trigonus was reported from Florianópolis.

[2][13]: 67 In the subsequent decades, triangle barnacles were reported from elsewhere in Brazil and in Madeira, the Azores, Guinea, and the Congolese coast.

[13]: 72  Today, its spread across the east American coast may be causing the decline of a related species, Balanus calidus.

[13]: 71 A report on the voyage of the HMS Challenger in the 19th century tentatively identified some Javan fossils dating to what was then known as the Tertiary period as representing B.

[19]: 457  A later study found that higher water temperatures (28 °C) caused the nauplii to metamorphose into cyprids more quickly, in less than six days.

When these conditions were combined, creating an environment with high temperature but lower salinity, the larvae metamorphosed quickly, but less than one third of the subsequent cyprids then attached themselves to the substrate.

The barnacles are able to assimilate and retain large amounts of metals they may get from their diets, such as zinc and cadmium, successfully into their bodies.