This slab was found in he middle triassic layers of Crailsheim, Germany. There are many remainings of Crinoids (on both sides) and several stings and jaw-parts of Echinoids.
The stone is unbroken, it measures about 26 x 20 x 2 cm.
Middle triassic Echinoids are very hard to find, complete examples cost more than 1000,- Euros.