Puntillitas are tiny ( not juvenile) Calamares. The next size down from Chipirones. They are usually served coated in “frying flour” (farina de freir) and deep fried. The oil must be hot and the excess flour shaken off otherwise they can become greasy. The name is a diminutive of the word “punta”, which means point and refers to the shape of this tiny cephalopod.
Some people like a squeeze of lemon but my understanding is that this is truly optional and left to the discretion of the individual. Never squeeze lemon over the whole platter.