Deep under the sea... aragonite

This banded aragonite has formed on the sea-floor by compression of all kind of small skeletons and shells of living creatures. Photo in SW UV

Locality: Millau, Aveyron, Midi-Pyrénées, France.

As the second photo shows, the creatures may very well fluoresce during their lifetime too. Living coral, fluorescing under LW-UV

Locatlity: Maui Ocean Center at Malaea, Maui, Hawaii, USA (2013).

Source: Fluorescent Minerals Workgroup MKA.