Need crab and urchin ID please...

Found these guys at Ko Saak (near Pattaya, Thailand). Depth around 8 msw.

I was told the crab is Dorippe dorsipes. Not sure if this is correct...

Would appreciate it if someone could ID the urchin too, please.

I don't know about the crab, but the sea urchin looks very much like the Pseudoboletia indiana that are quite common around Sydney. They have a fairly wide distribution that would include Thailand.

The tips on the ones here aren't quite as purple, more of a pink.

Hi Vie -- Dorippe dorsipes does occur in Thailand so that's good possibility. There are a bunch of these carrier crabs and I doubt if they can be reliably identified to species from a photo. Most of the photographed ones are identified as Dorippe frascone or Ethusa but that's because they're the only two carrier crabs in the Gosliner-Behrens-Williams book. Can't help with the urchin, sorry.