"Baltic photic hard clay characterized by no macroscopic biotic structures"@en . . "SDN:M23::AA-B4" . "The habitat 'Baltic photic hard clay characterized by no macroscopic biotic structures' as defined under the HELCOM HUB classification system. For more information visit 'http://helcom.fi/baltic-sea-trends/biodiversity/helcom-hub/hub/aa-b4'."@en . .