Collecting one of each class of echinoderm

[pefty]

So...... let's say I wanted to collect one specimen of each class of echinoderms (yes, the classes are always in flux, I know). Not a great specimen, just some ossicle or fragment easily determinable to be a member of that class for each class. It would be a fun trip around the world going to a set of localities, each of which was the easiest place in the world to find specimens of some particular echinoderm class. Some classes (crinoids, echinoids) seem almost too easy; others (blastoids, cyclocystoids, paracrinoids) are hard in some parts of the world but trivially easy here in eastern Missouri, USA. But more obscure classes of echinoderms (ctenocystoids, cinctans, solutans, stylophorans) seem to be hard to find no matter where you go; for each of these, I'm curious what formation / location would be the *least* hard. 

 

So let's start with a weird one: Where in the world is it *least difficult* to find a fossil readily determinable as belonging to an ophiocistioid? 

[TqB]

Good question! From the few papers I've read they typically seem to be chance rare finds, especially articulated ones. Gotland has yielded a relatively high number of Silurian goniodonts - more than 30 were collected for this paper.
https://www.researchgate.net/publication/258867342_Ophiocistioids_and_holothurians_from_the_Silurian_of_Gotland_Sweden

I suspect the goniodonts are more common than they appear from the records as they're easily overlooked; I've found three separate Anguloserra specimens in my local Brigantian (N.E England) where they're unrecorded and it took me years to find out what they were. 
This post:
https://www.thefossilforum.com/topic/90987-goniodonts-strange-echinozoan-teeth-from-the-carboniferous/#comment-997283 

Edited January 26 by TqB
typo

[pefty]

Love it, TqB. I'll see you in Gotland

 

Next: Is there anyplace to go to reliably find and collect identifiable ossicles or articulated specimens of any of the homalozoan classes, including ctenocystoids, cinctans, solutans, or stylophorans?

[Tidgy's Dad]

Homalozoa is no longer a recognized taxon if I am up to date.

You will need to look up the classes and orders separately.