This newly discovered animal reveals a unique lineage from 30 million years ago.

Fossils preserved in Dominican amber reveal a new family, genus and species of microinvertebrate from the mid-Tertiary period.

Fossils preserved in amber have revealed a new family, genus and species of microinvertebrate dating back 30 million years.

Informally, the new animals have been dubbed ‘mold pigs’, or more scientifically as Sialomorpha dominicana.

Measuring in at approximately 100 micrometres long, the mini pig-like critters had flexible heads, four pairs of legs and were clawless. The species grew by shedding their exoskeleton and ate fungi as well as other small invertebrates.

Several hundred individual mold pig fossils were found in the amber by George Poinar Jr. from Oregon State University, who says they shared warm, moist surroundings with pseudoscorpions, nematodes, fungi and protozoa.

"The large number of fossils provided additional evidence of their biology, including reproductive behaviour, developmental stages, and food," he adds.

"There is no extant group that these fossils fit into, and we have no knowledge of any of their descendants living today. This discovery shows that unique lineages were surviving in the mid-Tertiary."