Stardew Valley: How Many Purple Starfish Are There on Ginger Island?

Professor Snail, located on Ginger Island, gives you an Island Survey that consists of two questions. The second question he asks is How many purple starfish can be found on the island?

Professor Snail then gives you eight different answers to choose from. The correct answer to the question is 18.

A scroll with the text "How many purple starfish are there on Ginger Island?"