Pink Puffball Sponge

Image: Min Sheng Khoo
Oceanapia sagittaria

I had no idea something like this existed. It's an underground sponge!

On the surface, these sponges appear as nothing more than a stalk up to 10 cm (4 in) long topped by a prickly, lacy ball barely 2 cm (an inch) across. It all emerges from the sandy seabed of warm Pacific waters from India to Australia.

Image: Ria Tan

But what you wouldn't realise is that this is but the tip of a huge, pink and meaty iceberg! The real sponge is buried in the ground, where it presumably filters out tasty bacteria from the surrounding mud. Although how it does that without getting clogged up I have no idea...

The little puffball seems to be where the sponge exhales the water it has taken in, so it's a puffball that really puffs. The sponge also uses it to disperse budding, baby Pink Puffball Sponges into the sea. Basically, it's their only contact with the outside world!

Usually the "only contact with the outside world" is a row of iron bars, but I suspect a lot of prisoners would prefer that to a pink puffball. For various reasons.

Image: Ria Tan

And that's about all I could find out! This little bauble keeps its secrets close to its... giant heap of unspecialised cells. And underground. That's the main thing!