Complete set of 12 shapes formed by this puzzle's black squares

Question:

Answer:

PENTOMINOES

Length:

Similar Crossword Questions:

How this puzzle's black squares are arranged
Web concerns ... and based on six familiar names hidden in rows 1, 4, 12 and 15 of this puzzle grid, what the black squares in those rows symbolize
Like aleph in the central black squares of this puzzle's grid
Row of black squares preceding or following six puzzle answers, thereby completing them
Trains, in a way, and the key to 18 of this puzzle's black squares. (Ones that begin with the keyword are asterisked. The others are for you to discover.)
On hold ... or what the seven rows of black squares in this puzzle's grid spell in Morse code
Welcome mat spot (our puzzle title hints at the theme revealed by the pattern of circled squares)
Higher septet of black squares in this grid, typographically
Secret get-together, or what occurs literally in each of this puzzle's circled squares
Words of reproach, and a hint to how the four longest puzzle answers are formed
What the highlighted squares in this puzzle represent
Complete a crossword puzzle
Mail conveniences ... or a hint to eight squares in this puzzle
Like some crossword-puzzle squares
Apt word to substitute for each of four black squares to make sense of the across answers on either side of them
Daily crosswords, to puzzle pros (so-called from the number of squares per side)
Request that will complete the show's puzzle
Question asked by a customs officer or a kid on Christmas ... with a hint to this puzzle's circled squares
The 2x2 black square near the middle of this puzzle's grid, e.g., which is part of eight answers
Alice Walker novel ... or a hint to 12 squares in this puzzle
What you're doing as you complete this puzzle
Fills, as black squares
Hint to filling in four squares in this puzzle
What's been deposited in four squares of this puzzle, expressed both by name and by symbol
"Hmmmmm ..." [as hinted at by the three groups of black squares in the middle of the grid]