The exact cause of death for a mother Pygmy sperm whale, that came ashore last week in the Lake Arrowhead area of Horry County with her calf, continues to remain a mystery.

A necropsy showed the mother did have a common heart condition for that species, which could have contributed to her death, said Robert Young, a marine science professor with Coastal Carolina University.

Results of the necropsy showed an enlarged ventricle of her heart, Young said Tuesday.

“That’s common for strandings of that species that may have been a cause of death, but it’s not definitive,” Young said.