Lobster pots

A lobster pot is a portable device that is used by fishermen to trap crustaceans.  They are usually constructed of wire and wood. An opening permits the lobster to enter a tunnel of netting. Pots are usually constructed in two parts, called the "chamber" or “kitchen”, where there is bait, and exits into the “parlour”, where it is trapped from escape. Lobster pots are usually dropped to the sea floor about a dozen at a time, and are marked by a buoy so that they can be recovered later.

[Wikipedia]