The Carolina heelsplitter (Lasmigona decorata) is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae.

It is named the "Carolina heelsplitter" because in life the sharp edge of the valves protrudes from the substrate and could cut the foot of someone walking on the river or stream bed.

The IUCN Red List website states that to be considered critically endangered, the species must face an extremely high risk of becoming extinct in the wild in the immediate future.

The younger individuals tend to have faint black or greenish-brown rays on the outer surface of the shell.

The reasons stated were: “Present or threatened destruction, modification, or curtailment of its habitat or range”, “over utilization for commercial, recreational, scientific, or educational purposes”, “disease or predation”, “the inadequacy of existing regulatory mechanisms”, and “other natural or manmade factors affecting its continued existence”.

The recovery plan also stated that it was very important that the species were extensively enough established so the population couldn't be completely wiped out by one major event involving their habitat.

The reproductive cycle begins when the male Carolina heelsplitter releases its sperm into the stream.

When they have grown into fully developed juvenile mussels, they release themselves from the fish and settle into the stream or river.

A fish host is very important to all mussels, not only because it provides the young with food and oxygen, but also because it serves as a mode of transportation.

John A. Fridell also mentions that the populations are very highly fragmented and isolated, and that they have also only been found in short stream reaches of each other.

The biggest reasons for their critical endangerment are due to sedimentation and stream pollution, road construction and maintenance, runoff, mining, and several other human generated problems.

The research group thought that the higher levels of copper were due to more suspended sediment because of a recent rain downpour.

The vegetation along the river and stream sides also helps regulate the water's temperature during the long and hot summers.

Such human interventions as channelization, impoundments and stream dredging harm the species by directly destroying its habitat.