A sea star has 2 stomachs, the cardiac stomach and the pyloric stomach. It can push the cardiac stomach out of its mouth, in the centre of its underside, to engulf prey or insert it into prey (between 2 shells, for example). The stomach then secretes a powerful digestive enzyme to break down the prey.
When the cardiac stomach comes back into the body, the food in it is transferred to the pyloric stomach.
Acknowledgement: University of Waikato