Echinocorys are an extinct genus of echinoids and are a common fossil often found in the Cretaceous chalk deposits of the UK, this particular specimen however is a little unique in that it is partially within a flint nodule. At present, geologists are still not 100% certain how flint forms. However, the current and most widely accepted theory is that flint is derived from soft tissue material which has become trapped within sediment (chalk or limestone) and mineralises into flint during diagenesis, which is the process of a sedimentary rock becoming another sedimentary rock. This theory is accepted as it explains many of the fossils found within flint nodules, almost preserved similar to insects in amber. If this theory is true, then this particular fossil specimen could in fact exhibit an echinoid which had become buried in a marine sediment and it's soft tissues were squeezed out, eventually forming this partial flint nodule. Although this is merely a theory. Never the less, it is certainly a strange and unique fossil, measuring 90 x 50 x 100 mm in size, it was collected in Folkstone, Kent, UK, and will be an excellent addition to any serious fossil collection.