21405 is a postalcode and its consensus geometry is derived from uszcta.
{"mz:is_ceased":0,"geom:latitude":39.030474,"wof:name":"21405","counts:names_total":0,"wof:placetype":"postalcode","mz:is_current":1,"wof:hierarchy":[{"continent_id":102191575,"country_id":85633793,"county_id":102083469,"postalcode_id":554785871,"region_id":85688501}],"mz:is_deprecated":0,"lbl:latitude":39.02751,"mz:postal_locality_alt":["Sherwood Forest"],"geom:area":4.7E-4,"geom:longitude":-76.551459,"wof:id":554785871,"counts:concordances_total":1,"geom:type":"Polygon","wof:lastmodified":1611183509,"wof:belongsto":[102191575,85633793,102083469,85688501],"wof:concordances":{"gp:id":"12766564"},"wof:repo":"whosonfirst-data-postalcode-us","src:geom":"uszcta","wof:country":"US","counts:names_preferred":0,"gp:parent_id":"2354877","geom:area_square_m":4516164.370047,"wof:tags":[],"counts:names_variant":0,"wof:breaches":[],"edtf:inception":"uuuu","iso:country":"US","counts:names_languages":0,"geom:bbox":"-76.570564,39.017669,-76.529878,39.040506","wof:superseded_by":[],"wof:supersedes":[],"lbl:longitude":-76.556716,"wof:geomhash":"a7a9dde0648cf780d54a3488a16b873a","wof:parent_id":102083469,"wof:placetype_names":["postalcode"],"mz:hierarchy_label":1,"wof:placetype_id":470996387,"edtf:cessation":"uuuu","mz:postal_locality":"Annapolis"}