Find the category that fits best for the specimen you want to identify:
1
Crusts or cover on rock, or rugged or loose-laying irregularly branched lumps of calcified algae go to subkey
2
Thallus upright with round (or rounded) axis or axes in cross section,
not flat in any part go to subkey
3
Thallus upright and flat or with some flat or flattened parts go to subkey
