do the pentapods wear clothes? do they feel the need to hide their stabby genitals with them?

Nope! They be walking around in the buff out here! Mostly because their planet is a literal slime ball, so everything is sticky and wet. The closest thing to clothes would be armor/protective pieces. And those are few and far between. Terrestrial pentapods still retain a layer of mucus over their skin to help prevent the floor growing on them! Damaging that film can lead to big trouble if you are not diligent in keeping it clean/slap some excess slime from your buddy on there.

Also! The stabbing portion of their junk is retracted most of the time and it is a big no no to have it out in the majority of social settings. Luckily for that it is voluntarily controlled so they don’t have to worry about getting caught with their nonexistent pants down!

I love your pentapods! Theyre really cute. I have cephalopod-like aliens myself that walk on their tentacles on land, and I'm wondering if the tentacles need a rigid internal structure to be able to support their weight on land, like spines or something.

Ah thank you! Terrestrial tentacles are ALWAYS choice! And while I don’t know about NEEDING a super rigid internal support I gave mine something kinda like that!

Not like anything as hard as bone but a little bit of cartilage to mostly house the big nerves and blood vessels and support the actual weight a bit more. I think that’s the biggest issue with tentacles. They can sploot out under the body a lot easier than a rigid skeleton. It all comes down to what feels right, less gravity will be a lot easier on a squishy limb!