yantra
s='sn'> : an envelope often largely of silk which an insect larva forms about itself and in which it passes the pupa stage
: any of various other protective coverings produced by animals
: something suggesting a cocoon especially in providing protection or in producing isolation //wrapped in a cocoon of blankets //an interest in the world beyond the everyday cocoon most of us construct — Peter Mayle
: a protective covering placed or sprayed over military or naval equipment in storage