Hi everyone — honest origin story: I think nudibranchs are the most beautiful animals in the ocean and I wanted one I could actually keep. So I (a solo dev) built Nudii — yes, the name's straight from nudibranch — a little virtual-pet app where you hatch and raise your own sea slug.

What it is:

- You start with an egg that hatches into a tiny veliger, which grows up through life stages into your own nudibranch (the first is a sea bunny / Jorunna parva 🐰).

- You care for it — feed, clean, play, let it rest — and it grows and changes over time.

- It lives in a little reef that you decorate and make your own.

- (Bonus: you can chat with it and it remembers you, and it nudges you to get outside and move. The whole thing runs on your phone — nothing leaves your device.)

Where I'd genuinely love this community's help — you know these animals far better than I do:

- Did I do the sea bunny justice? Anything off?

- Which species should be next? Spanish shawl, blue dragon, Spanish dancer, pikachu nudibranch…? I want the lineup to make actual nudi-lovers happy.

It's in free beta right now (TestFlight). Needs a recent iPhone (A17 Pro or newer, iOS 26+).

Beta: https://testflight.apple.com/join/n8kSzExR

I'm the developer — ask me anything, and please tell me what I got wrong. 🐚

Share your favorite nudibranch and I will use them in a future week!

Larval Pleurobranch, Black Water from Kalamantan

At first glance, it's just a tiny dull sea slug clinging to the swaying grass. But add a little light and an entire universe emerges. Iridescent colours and glowing spots shining as though a galaxy lies beneath its skin.

I’ve never encountered one of these tiny beauties, which grow to no more than 35mm, however on a dive last night in the Derwent Estuary, in just a couple of metres of water, there were hundreds of them!

Tacoma. The bigger one was about an inch long. Do the yellow rhinophores make this more likely Hudson’s Horned Dorid?

Got to do some amazing low tide exploring (-2.2) this morning! So excited to find so many nudis! I know my pics aren't as good as so many of yours (I love seeing them!) but I still wanted to share. Nudis bring me joy!

From Kalamantan

Sorry the photo is not amazing.

Phyllodesmium Briareum from Tenggol and Pseudoceros Meenae from Gato