Large Document Format (PSB)The Large Document Format (PSB) supports documents up to 300,000 pixels in any dimension. All Photoshop features, such as layers, effects, and filters, are supported. (With documents larger than 30,000 pixels in width or height, some plug-in filters are unavailable.) You can save HDR, 32-bits-per-channel images as PSB files. Smart Object layer is saved as .psb. Once you double-click you should see the nested layers, and how it was created. I bet the ornament shape is a clipping-mask. How to create a Clipping Mask: Arrange the layers in the Layers panel so that the base layer with the mask is below the layers that you want to mask.
Do one of the following: 1. Hold down Alt (Windows) or Option (Mac OS), position the pointer over the line in the Layers panel dividing the base layer and the first layer above it that you want to include in the clipping mask (the pointer changes to two overlapping circles ), and click. or 2. Select the first layer above the base layer in the Layers panel, and choose Layer > Create Clipping Mask.
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