Yes, Murano, but impossible to date or attribute to maker. Many companies, some, famous, Fratelli Toso and Barbini, for example, and some less famous made shell-type bowls like this. As Andy McConnell writes in Miller's 20th century Glass ( a book I think you'd find very useful), Murano makers "routinely copied" each others' work, believing they were paying a compliment to the other designer. Another book that would help identify the Murano you come across is Pina's Italian Glass: Century 20. I found having these books saved me a lot of internet searching and helped me develop a better eye for picking out glass.