It only looks like a colon from above.
Source unknown (emailed to me).
A tip of the blogging hat to reader Drabkikker, who found the source. And I learn some new terminology:
A loveseat can be one of two styles of two-seat chair.One form – also known as "British two-seaters" – is essentially synonymous with "two-seat couch". It typically has two upholstered seats.Another form, variously also known as a tête-à-tête, courting bench, kissing bench, gossip's chair, or conversation bench, is any form of two-seat furniture where the two seats are arranged in an S shape, so that two persons can converse while looking at each other and being within arm's reach, while at the same time typically retaining a modest barrier between them.
Addendum: A tip of the blogging cap to reader fabs, who commented that "In Mérida, México they are very popular and they are called "confidants" or "you and me." You can see them in many public parks and along the most representative avenue of the city called Paseo Montejo. Here's a photo from a report at Historical Mexico: