expression, godan verb (-su)
bask in the sun lying on one's stomach
Idiomatic expression literally meaning 'to dry one's shell', used for sunbathing while lying face down. Often associated with turtles or a relaxed, lazy posture.
See also: 甲羅干し
夏のビーチで、彼は甲羅を干すように寝そべっていた。
At the summer beach, he was lying on his stomach as if basking in the sun.
亀が岩の上で甲羅を干している。
A turtle is basking in the sun on a rock.