Magick::Image.read #=> arrayなんでarrayなんだっけなって

はい

An array containing 0 or more Image objects. If the file is a multi-image file such as an animated GIF or a Photoshop PSD file with multiple layers, the array contains an Image object for each image or layer in the file.

http://www.imagemagick.org/RMagick/doc/image1.html#read