What Is It?

I was at the Tropical Greenhouse at my local park recently, and when I looked on the ground, they had a very large container with these growing in it. I instantly thought of mangroves, because of how these grow in the ground in water. I know that is not what they are, they're probably a fruit of some kind, but am really unclear what exactly I was looking at here. 

Do any of you know what these are?

For more 'Ground' photos, visit Thursday Challenge