This starfish is called a Sea Star or Asteroid. They have five arms, which can regenerate if broken off. Occasionally a new starfish can develop from a broken off arm. The mouth is on the bottom and the anus is on top. Some sea stars have the ability to stick their stomachs outside their moths and put it around their prey (often a conch) and digest it from the outside before returning their (now full) stomach to where it belongs.