Borneo has the best fauna. There are tiny rainforest Opisthostoma, whose spikes and flares foil predatory slugs. And there are vivid green slugs and snails.
A semi-slug has a shell that's too small to protect anything but the most delicate body parts. Now you see it.
Now you don't.
This snail's shell is transparent. The green colour comes from the surface of the mantle.
And while you're there, have a look at some of the other extraordinary invertebrates in that part of the world. And then book your flight to Kota Kinabalu.
Thanks to Budak for the link.