These are made using real specimen 3D scan data from the Smithsonian. A collection of gorgeous sea critters turned into brooches/pins.

Check out the rest of the Smithsonian's downloadable CC0 Open Access data:  https://3d.si.edu/explore?edan_fq%5B0%5D=media_usage%3A%22CC0%22 

These pins are made from the following digitized collections objects: 

• Pycnopodia helianthoides (1/3 scale) https://3d.si.edu/object/3d/pycnopodia-helianthoides:0c69e749-b8df-4e5a-8d20-c38aebaf6279
• Balanus psittacus (1/4 scale) https://3d.si.edu/object/3d/balanus-psittacus:b78ece08-53cb-4623-b6d3-10f76fb74967
• Madracis formosa (1/4scale) https://3d.si.edu/object/3d/madracis-formosa:78c14966-ff41-4a1d-98f4-359931135112
• Rotula deciesdigitata (full scale) https://3d.si.edu/object/3d/rotula-deciesdigitata:86c2ccf4-2f29-4c1c-845d-42ee8f92eec5
• Astraea heliotropium (1/2 scale) https://3d.si.edu/object/3d/astraea-heliotropium:6e5ce6b4-ca94-4ae6-b367-62534fa079db 

It's recommended to print these pins at .08mm Extra Fine to take advantage of the gorgeous details!
Printed with this setting in matte PLA, they fit with these pin blanks: https://www.amazon.com/dp/B0B7JNVGWK?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1 
They are somewhat pressure fit, and I backed it up with this super glue: https://www.amazon.com/dp/B0CBSGWZRW?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_3&th=1