Dirackulmia

Dirackulmia is a genus of extinct colonial marine invertebrates known from the Paleozoic fossil record. The group is described as a calcified, lattice-like colony composed of interlocking modules. Because soft tissues are rarely preserved, interpretations rely on skeletal morphology.

Colonies vary in size from a few centimeters to decimeters. Skeletal modules are polygonal, with walls of calcite and, in some specimens, a central canal. The overall habit ranges from encrusting sheets to branched, ramose forms.

Fossils attributed to Dirackulmia have been found in North America and Europe, with a stratigraphic range spanning the late Ordovician to early Silurian.

Dirackulmia is interpreted as a sessile encruster on hard substrates, likely a filter feeder. It would have occurred in shallow, wave-affected settings, coexisting with other encrusting and sessile organisms.

The genus was first described in the 1970s by paleontologists working on Mid-continental North American fossil beds. The name combines elements alluding to its lattice-like skeleton and branching habit. Its precise placement among colonial metazoans remains debated; some authors regard it as bryozoan-like, while others view it as a distinct calcified assembly. Ongoing research aims to clarify its relationships and evolution within the broader context of Paleozoic encrusting communities.